Speed skating at the 1972 Winter Olympics was a series of skating events whose results are below. They happened at the Olympic Games in Sapporo, Japan.

500 m

February 5, 1972 — 38 competitors from 16 countries

RANK	NAME ATHLETE	TIME
		39.44
		39.69
		39.80
4.		39.91
5.		40.12
6.		40.14
7.		40.25
8.		40.35

1,500 m

February 6, 1972 — 39 competitors from 16 countries

RANK	NAME ATHLETE	TIME
		2:02.96
		2:04.26
		2:05.89
4.		2:05.94
5.		2:06.58
6.		2:07.16
7.		2:07.24
8.		2:07.43

5,000 m

February 4, 1972 — 28 competitors from 14 countries

RANK	NAME ATHLETE	TIME
		7:23.61
		7:28.16
		7:33.39
4.		7:36.17
5.		7:36.47
6.		7:39.17
7.		7:39.26
8.		7:39.40

10,000 m

February 7, 1972 — 24 competitors from 14 countries

RANK	NAME ATHLETE	TIME
		15:01.35
		15:04.70
		15:07.08
4.		15:17.99
5.		15:20.08
6.		15:30.19
7.		15:38.87
8.		15:43.92

500 m

February 9, 1972 — 30 competitors from 12 countries

RANK	NAME ATHLETE	COUNTRY	TIME
	Anne Henning Anne Henning Anne Elizabeth Henning is a former speed skater from the United States.Anne Henning grew up in Northbrook, Illinois and started in short track speed skating, but then, like many short track speed skaters before and after her, switched to long track speed skating...	USA	43.33
	Vera Krasnova Vera Krasnova Vera Ivanovna Krasnova is a Russian speed skater who competed for the Soviet Union in the 1972 Winter Olympics and in the 1976 Winter Olympics.She was born in Omsk.In 1972 she won the silver medal in the 500 metres event....	URS	44.01
	Lyudmila Titova Lyudmila Titova Lyudmila Evgenevna Titova is a former speed skater.-Short biography:She trained at Burevestnik and later at Zenit sports societies. Skating for the Soviet Union, Lyudmila Titova made her international debut at the World Allround Championships of 1966...	URS	44.45
4.	Sheila Young Sheila Young Sheila Grace Young-Ochowicz is a former speed skater and track cyclist from the United States.-Short biography:...	USA	44.53
5.	Monika Pflug Monika Pflug Monika Pflug , also known as Monika Holzner-Pflug and Monika Gawenus-Pflug, is a former speed skater from Germany. She was born in Munich and competed for West Germany....	FRG	44.75
6.	Atje Keulen-Deelstra Atje Keulen-Deelstra Atje Keulen-Deelstra is a former speed skater.Keulen-Deelstra was born in Grouw, the Netherlands. When she was 16 years old, Deelstra already won a junior title of Friesland. She practised many sports during those days, but speed skating was her favourite and she won many cash prizes in the...	NED	44.89
7.	Kay Lunda	USA	44.95
8.	Alla Butova	URS	45.17

1,000 m

February 11, 1972 — 33 competitors from 12 countries

RANK	NAME ATHLETE	COUNTRY	TIME
	Monika Pflug Monika Pflug Monika Pflug , also known as Monika Holzner-Pflug and Monika Gawenus-Pflug, is a former speed skater from Germany. She was born in Munich and competed for West Germany....	FRG	1:31.40
	Atje Keulen-Deelstra Atje Keulen-Deelstra Atje Keulen-Deelstra is a former speed skater.Keulen-Deelstra was born in Grouw, the Netherlands. When she was 16 years old, Deelstra already won a junior title of Friesland. She practised many sports during those days, but speed skating was her favourite and she won many cash prizes in the...	NED	1:31.61
	Anne Henning Anne Henning Anne Elizabeth Henning is a former speed skater from the United States.Anne Henning grew up in Northbrook, Illinois and started in short track speed skating, but then, like many short track speed skaters before and after her, switched to long track speed skating...	USA	1:31.62
4.	Lyudmila Titova Lyudmila Titova Lyudmila Evgenevna Titova is a former speed skater.-Short biography:She trained at Burevestnik and later at Zenit sports societies. Skating for the Soviet Union, Lyudmila Titova made her international debut at the World Allround Championships of 1966...	URS	1:31.85
5.	Nina Statkevich Nina Statkevich Nina Andreyevna Statkevich is a former speed skater who competed for the Soviet Union.Nina Statkevich trained at VSS Trud in Leningrad. She won many titles – she was World Allround Champion, European Allround Champion twice, Soviet Allround Champion four times, and Soviet Sprint Champion...	URS	1:32.21
6.	Dianne Holum Dianne Holum Dianne Mary Holum is a former speed skater.In 1967, at the age of 15, Dianne Holum won bronze at the World Allround Championships. At the age of 16, Holum earned a silver medal in the 500 meter race at the 1968 Winter Olympics, finishing in a three way tie for second place...	USA	1:32.41
7.	Ellie van den Brom	NED	1:32.60
8.	Sylvia Burka Sylvia Burka Sylvia Burka is a former ice speed skater from Canada of Latvian descent, who represented her native country at three consecutive Winter Olympics, starting in 1972 in Sapporo, Japan....	CAN	1:32.95

1,500 m

February 10, 1972 — 31 competitors from 12 countries

RANK	NAME ATHLETE	COUNTRY	TIME
	Dianne Holum Dianne Holum Dianne Mary Holum is a former speed skater.In 1967, at the age of 15, Dianne Holum won bronze at the World Allround Championships. At the age of 16, Holum earned a silver medal in the 500 meter race at the 1968 Winter Olympics, finishing in a three way tie for second place...	USA	2:20.85
	Stien Baas-Kaiser Stien Kaiser Christina Wilhelmina Baas-Kaiser is a former speed skater from the Netherlands....	NED	2:21.05
	Atje Keulen-Deelstra Atje Keulen-Deelstra Atje Keulen-Deelstra is a former speed skater.Keulen-Deelstra was born in Grouw, the Netherlands. When she was 16 years old, Deelstra already won a junior title of Friesland. She practised many sports during those days, but speed skating was her favourite and she won many cash prizes in the...	NED	2:22.05
4.	Elly van den Brom	NED	2:22.27
5.	Rosemarie Taupadel	GDR	2:22.35
6.	Nina Statkevich Nina Statkevich Nina Andreyevna Statkevich is a former speed skater who competed for the Soviet Union.Nina Statkevich trained at VSS Trud in Leningrad. She won many titles – she was World Allround Champion, European Allround Champion twice, Soviet Allround Champion four times, and Soviet Sprint Champion...	URS	2:23.19
7.	Connie Carpenter	USA	2:23.93
8.	Sigrid Sundby Sigrid Sundby Sigrid Sundby was a Norwegian speed skater who competed internationally in the 1960s and 1970s.She competed at the Winter Olympics in 1968, 1972 and 1976. Her best Olympic results were 4th in the 1500 metres, 6th in 500 metres, and 6th in 1000 metres at the 1968 Winter Olympics in Grenoble...	NOR	2:24.07

3,000 m

February 12, 1972 — 23 competitors from 10 countries

RANK	NAME ATHLETE	COUNTRY	TIME
	Stien Baas-Kaiser Stien Kaiser Christina Wilhelmina Baas-Kaiser is a former speed skater from the Netherlands....	NED	4:52.14
	Dianne Holum Dianne Holum Dianne Mary Holum is a former speed skater.In 1967, at the age of 15, Dianne Holum won bronze at the World Allround Championships. At the age of 16, Holum earned a silver medal in the 500 meter race at the 1968 Winter Olympics, finishing in a three way tie for second place...	USA	4:58.67
	Atje Keulen-Deelstra Atje Keulen-Deelstra Atje Keulen-Deelstra is a former speed skater.Keulen-Deelstra was born in Grouw, the Netherlands. When she was 16 years old, Deelstra already won a junior title of Friesland. She practised many sports during those days, but speed skating was her favourite and she won many cash prizes in the...	NED	4:59.91
4.	Sippie Tigchelaar	NED	5:01.67
5.	Nina Statkevich Nina Statkevich Nina Andreyevna Statkevich is a former speed skater who competed for the Soviet Union.Nina Statkevich trained at VSS Trud in Leningrad. She won many titles – she was World Allround Champion, European Allround Champion twice, Soviet Allround Champion four times, and Soviet Sprint Champion...	URS	5:01.79
6.	Kapitolina Seregina	URS	5:01.88
7.	Tuula Vilkas	FIN	5:05.92
8.	Lyudmila Savrulina	URS	5:06.61

  Australia

Australia at the 1972 Winter Olympics

Australia competed at the 1972 Winter Olympics in Sapporo, Japan.Malcolm Milne, who won an international downhill race at Val d'Isère, France in 1970, almost fell during the downhill race, denying him a chance at an Olympic medal.-Alpine skiing:...

1. Colin Coates
   Colin Coates
   Colin Victor Coates is a former ice speed skater from Australia, who represented his native country in – a record – six consecutive Winter Olympics, starting in 1968 in Grenoble, France....
   
   
2. Jim Lynch

  Canada

Canada at the 1972 Winter Olympics

Canada competed at the 1972 Winter Olympics in Sapporo, Japan. Canada has competed at every Winter Olympic Games.-Medalists:- Alpine skiing:MenMen's slalomWomen- Bobsleigh:- Cross-country skiing:MenMen's 4 x 10km relay...

1. Andrew Barron
2. Sylvia Burka
   Sylvia Burka
   Sylvia Burka is a former ice speed skater from Canada of Latvian descent, who represented her native country at three consecutive Winter Olympics, starting in 1972 in Sapporo, Japan....
   
   
3. Gerard Cassan
4. John Cassidy
5. Gayle Gordon
6. Bob Hodges
7. Jennifer Jackson
8. Donna McCannell
9. Cathy Priestner
   Cathy Priestner
   Catherine Ann Priestner is a Canadian who won a silver medal in Speed skating at the 1976 Winter Olympics. She also competed in the 1972 Winter Olympics. She was inducted into the Canadian Olympic Hall of Fame in 1994. Priestner competed in her first competition at the age of 15.- References :...
   
   
10. Kevin Sirois

  East Germany

East Germany at the 1972 Winter Olympics

East Germany competed at the 1972 Winter Olympics in Sapporo, Japan.-Medalists:- Biathlon:Men1One minute added per close miss , two minutes added per complete miss....

1. Ruth Budzich-Schleiermacher
   Ruth Schleiermacher
   Ruth Schleiermacher is a former East German speedskater. She took part in eight international championships...
   
   
2. Rosemarie Taupadel

  Finland

Finland at the 1972 Winter Olympics

-Medalists:- Biathlon:Men1One minute added per close miss , two minutes added per complete miss.Men's 4 x 7.5 km relay2A penalty loop of 200 metres had to be skied per missed target.- Cross-country skiing:Men...

1. Seppo Hänninen
2. Arja Kantola
3. Kimmo Koskinen
4. Leo Linkovesi
   Leo Linkovesi
   Leo Ensio Linkovesi was a Finnish speedskater who specialised on the shorter distances, the 500 m and the 1000 m....
   
   
5. Jouko Salakka
6. Tuula Vilkas

  Great Britain

Great Britain at the 1972 Winter Olympics

The United Kingdom of Great Britain and Northern Ireland competed as Great Britain at the 1972 Winter Olympics in Sapporo, Japan.- Alpine skiing:MenMen's slalomWomen- Biathlon:Men...

1. John Blewitt
2. David Hampton

  Italy

Italy at the 1972 Winter Olympics

-Medalists:- Alpine skiing:MenMen's slalom- Biathlon:Men1One minute added per close miss , two minutes added per complete miss.Men's 4 x 7.5 km relay2A penalty loop of 200 metres had to be skied per missed target....

1. Giovanni Gloder
2. Bruno Toniolli

  Japan

Japan at the 1972 Winter Olympics

Japan was the host nation for the 1972 Winter Olympics in Sapporo. It was the first time that Japan had hosted the Winter Olympic Games, but second time overall after the 1964 Summer Olympics in Tokyo....

1. Akiko Ariga
2. Takayuki Hida
3. Norio Hirate
4. Kaname Ide
5. Kiyomi Ito
6. Satomi Koike
7. Mutsuhiko Maeda
8. Osamu Naito
9. Yoshiko Onozawa
10. Jitsuko Saito
11. Keiichi Suzuki
12. Masaki Suzuki
13. Emiko Taguchi

  Mongolia

Mongolia at the 1972 Winter Olympics

- Cross-country skiing:Men- Speed skating:Men-References:**...

1. Luvsanlkhagvyn Dasjnjam
2. Luvasansharavyn Tsend

  Netherlands

Netherlands at the 1972 Winter Olympics

Athletes from the Netherlands competed at the 1972 Winter Olympics in Sapporo, Japan.-Medalists:- Figure skating:- Speed skating:MenWomen-References:***...

1. Stien Baas-Kaiser
2. Jan Bols
   Jan Bols
   Jan Bols is a former Dutch long track speed skater.Bols was among the top all-rounders in the late 60s and early 70s, this period overlapped the glory days of Kees Verkerk and Ard Schenk, so that he tends to be known as the third best Dutch skater of his time.Bols participated in the 1968 and 1972...
   
   
3. Elly van den Brom
4. Jappie van Dijk
5. Atje Keulen-Deelstra
   Atje Keulen-Deelstra
   Atje Keulen-Deelstra is a former speed skater.Keulen-Deelstra was born in Grouw, the Netherlands. When she was 16 years old, Deelstra already won a junior title of Friesland. She practised many sports during those days, but speed skating was her favourite and she won many cash prizes in the...
   
   
6. Trijnie Rep
7. Ard Schenk
   Ard Schenk
   Adrianus "Ard" Schenk is a former speed skater from the Netherlands, who is considered to be one of the best in history. His first Olympic success came in 1968, when he won a silver medal at the 1968 Winter Olympics. Between 1970 and 1972 Winter Olympics, Schenk won three consecutive World...
   
   
8. Sippie Tigchelaar
9. Eddy Verheijen
10. Kees Verkerk
    Kees Verkerk
    Cornelis Arie Verkerk , better known as Kees Verkerk, is a former speed skater from the Netherlands.-Short biography:...
    
    

  North Korea

North Korea at the 1972 Winter Olympics

North Korea competed as the Democratic People's Republic of Korea at the 1972 Winter Olympics in Sapporo, Japan.- Speed skating:Women-References:**...

1. Choi Dong-Wuk
2. Han Pil-Hwa
   Han Pil-Hwa
   Han Pil-Hwa is a female North Korean speed skater who competed in the 1964 Winter Olympics and in the 1972 Winter Olympics....
   
   
3. Kim Bok-Sun
4. Kim Myeong-Ja
5. Kim Ok-Sun
6. Tak In-Suk

  Norway

Norway at the 1972 Winter Olympics

-Medalists:- Alpine skiing:MenMen's slalomWomen- Biathlon:Men1One minute added per close miss , two minutes added per complete miss.Men's 4 x 7.5 km relay...

1. Lisbeth Berg
2. Kirsti Biermann
   Kirsti Biermann
   Kirsti Biermann is a Norwegian speed skater, born in Oslo. She competed at the 1968 Winter Olympics in Grenoble, where she placed 8th in 500 m and 9th in 1000 m. She participated in four competitions at the 1972 Winter Olympics in Sapporo....
   
   
3. Per Bjørang
   Per Bjørang
   Per Bjørang is a former Norwegian speed skater and Sprint World Champion. At the 1972 Winter Olympics in Sapporo he finished 4th in the 500 metres. He became World Champion in sprint in 1974....
   
   
4. Lasse Efskind
   Lasse Efskind
   Lasse Daniel Efskind is a Norwegian medical doctor, primarily known for his speedskating career and his books. He is the son of Leif Efskind , professor of medicine at the University of Oslo and a pioneer in the field of heart operations.Efskind burst onto the international speedskating scene...
   
   
5. Dag Fornæss
   Dag Fornæss
   Dag Fornæss is a former speed skater from Norway who won the Norwegian, European, and World Allround Championships in 1969. He was born in Hamar.-Biography:...
   
   
6. Roar Grønvold
   Roar Grønvold
   Roar Grønvold is a former speed skater from Norway.Grønvold had his best year in 1972 when he became Norwegian Allround Champion and won silver at the Norwegian Sprint Championships...
   
   
7. Per Willy Guttormsen
   Per Willy Guttormsen
   Per Willy Guttormsen is a former Norwegian speed skater. He was among the world's best long distance skaters in the 1960s.Guttormsen's international breakthrough was his 6th place in the 1964 World Speed Skating Championships, at age 21. That year he was just outside the Norwegian three-man quota...
   
   
8. Ole Christian Iversen
   Ole Christian Iversen
   Ole Christian Iversen is a Norwegian speed skater. He was born in Lillehammer and represented the club Oslo IL. He competed in the 500 m at the 1972 Winter Olympics in Sapporo.-References:...
   
   
9. Johan Lind
   Johan Lind
   Johan Lind is a Norwegian speed skater. He was born in Mosjøen and represented the club Hamar IL. He competed in the 500 m at the 1968 Winter Olympics in Grenoble, and at the 1972 Winter Olympics in Sapporo.-References:...
   
   
10. Willy Olsen
    Willy Olsen
    Willy Olsen is a former Norwegian speed skater from Tynset who competed internationally in the 1970s. His strength was on the long distances, and he won the 5000 metres distance at the national championship in 1972...
    
    
11. Sten Stensen
    Sten Stensen
    Sten Einar Stensen is a former speed skater.-Short biography:Together with Amund Sjøbrend, Kay Stenshjemmet, and Jan Egil Storholt, Sten Stensen was one of the legendary four S-es , contemporary Norwegian top skaters in the 1970s and early 1980s...
    
    
12. Svein-Erik Stiansen
    Svein-Erik Stiansen
    Svein-Erik Stiansen is a former Norwegian speed skater. He represented Oslo Skøiteklub.He participated in the 1968 and 1972 Olympics, and in the 1968 Winter Olympics he finished 7th in the 1500 m and 12th in the 5000 m....
    
    
13. Sigrid Sundby
    Sigrid Sundby
    Sigrid Sundby was a Norwegian speed skater who competed internationally in the 1960s and 1970s.She competed at the Winter Olympics in 1968, 1972 and 1976. Her best Olympic results were 4th in the 1500 metres, 6th in 500 metres, and 6th in 1000 metres at the 1968 Winter Olympics in Grenoble...
    
    
14. Bjørn Tveter
    Bjørn Tveter
    Bjørn Tveter is a former Norwegian speed skater who competed internationally in the 1960s and 1970s. At the 1968 Winter Olympics in Grenoble he finished 5th in the 1500 metres...
    
    

  South Korea

South Korea at the 1972 Winter Olympics

South Korea, as Korea, competed at the 1972 Winter Olympics in Sapporo, Japan.-Figure skating:Women-Speed skating:MenWomen-References:*...

1. Choi Jung-Hyi
2. Jeon Seon-Ok
3. Jeong Chung-Ku
4. Lee Kyeong-Hyi

  Soviet Union

Soviet Union at the 1972 Winter Olympics

The Soviet Union competed at the 1972 Winter Olympics in Sapporo, Japan. The use of both the English alphabet and abbreviations threw it directly behind the USA in the Parade of Nations.-Medalists:- Alpine skiing:MenMen's slalomWomen...

1. Alla Butova
2. Vladimir Komarov
3. Vera Krasnova
   Vera Krasnova
   Vera Ivanovna Krasnova is a Russian speed skater who competed for the Soviet Union in the 1972 Winter Olympics and in the 1976 Winter Olympics.She was born in Omsk.In 1972 she won the silver medal in the 500 metres event....
   
   
4. Valery Lavrushkin
5. Valery Muratov
   Valery Muratov
   Valery Alekseyevich Muratov is a former ice speed skater from the USSR, who represented his native country in three consecutive Winter Olympics, starting in 1968 in Grenoble, France. He trained in Kolomna at Burevestnik and later at the Armed Forces sports society.In 1972 Muratov was awarded the...
   
   
6. Lyudmila Savrulina
7. Kapitolina Seregina
8. Nina Statkevich
   Nina Statkevich
   Nina Andreyevna Statkevich is a former speed skater who competed for the Soviet Union.Nina Statkevich trained at VSS Trud in Leningrad. She won many titles – she was World Allround Champion, European Allround Champion twice, Soviet Allround Champion four times, and Soviet Sprint Champion...
   
   
9. Lyudmila Titova
   Lyudmila Titova
   Lyudmila Evgenevna Titova is a former speed skater.-Short biography:She trained at Burevestnik and later at Zenit sports societies. Skating for the Soviet Union, Lyudmila Titova made her international debut at the World Allround Championships of 1966...
   
   

  Sweden

Sweden at the 1972 Winter Olympics

-Medalists:- Alpine skiing:MenMen's slalomWomen- Biathlon:Men1One minute added per close miss , two minutes added per complete miss.Men's 4 x 7.5 km relay...

1. Hasse Börjes
   Hasse Börjes
   Hasse Börjes is a Swedish speed skater, Olympic medalist and former world record holder in the 500m.At the 1972 Olympics in Sapporo Börjes was silver medalist on the 500 meter....
   
   
2. Göran Claeson
   Göran Claeson
   Göran Claeson is a former speed skater from Sweden.Claeson participated in the 1,500 m at the 1968 Winter Olympics of Grenoble, but finished only 20th. In 1969, at the first European Allround Championships in which Claeson participated, he won bronze. Three weeks later, at the first World...
   
   
3. Sylvia Filipsson
   Sylvia Filipsson
   Sylvia Filipsson is a former ice speed skater from Sweden, who represented her native country at the 1980 Winter Olympics in Lake Placid, United States.-References:...
   
   
4. Johan Granath
5. Johnny Höglin
   Johnny Höglin
   Johnny Höglin is a Swedish speed skater whose greatest moment was to win a gold medal in the 10,000-meter event at the 1968 Winter Olympics in Grenoble, France....
   
   
6. Ylva Hedlund
7. Ann-Sofie Järnström
8. Göran Johansson
9. Ove König
10. Örjan Sandler
    Örjan Sandler
    Örjan Sandler is a Swedish speed skater who competed in the 1964 Winter Olympics, in the 1968 Winter Olympics, in the 1972 Winter Olympics, in the 1976 Winter Olympics, and in the 1980 Winter Olympics.He was born in Sunne....
    
    
11. Mats Wallberg
    Mats Wallberg
    Mats Wallberg is a former ice speed skater from Sweden, who represented his native country in two consecutive Winter Olympics, starting in 1972 in Sapporo, Japan.-References:...
    
    

  United States

United States at the 1972 Winter Olympics

The United States competed at the 1972 Winter Olympics in Sapporo, Japan. The use of both the English alphabet and abbreviations threw the country directly in front of the USSR in the Parade of Nations.- Medalists :- Alpine skiing:Men...

1. Neil Blatchford
2. Connie Carpenter
3. Daniel Carroll
4. Peter Eberling
5. Charles Gilmore
6. Anne Henning
   Anne Henning
   Anne Elizabeth Henning is a former speed skater from the United States.Anne Henning grew up in Northbrook, Illinois and started in short track speed skating, but then, like many short track speed skaters before and after her, switched to long track speed skating...
   
   
7. Dianne Holum
   Dianne Holum
   Dianne Mary Holum is a former speed skater.In 1967, at the age of 15, Dianne Holum won bronze at the World Allround Championships. At the age of 16, Holum earned a silver medal in the 500 meter race at the 1968 Winter Olympics, finishing in a three way tie for second place...
   
   
8. Gary Jonland
9. Clark King
10. Bill Lanigan
11. Kay Lunda
12. Greg Lyman
13. Jean Omelenchuk
14. Leah Poulos
    Leah Poulos
    Leah Jean Poulos is a former speed skater.Leah Poulos specialized in the sprint events and made her international debut at the World Sprint Championships in 1970, where she won a silver medal in the 500 meter event...
    
    
15. John Wurster
16. Sheila Young
    Sheila Young
    Sheila Grace Young-Ochowicz is a former speed skater and track cyclist from the United States.-Short biography:...
    
    

  West Germany

West Germany at the 1972 Winter Olympics

West Germany competed at the 1972 Winter Olympics in Sapporo, Japan.-Medalists:- Alpine skiing:MenMen's slalomWomen- Biathlon:Men...

1. Paula Dufter
2. Erhard Keller
   Erhard Keller
   Erhard Keller is a former speed skater from Germany.Competing for West Germany, Keller specialised on the sprint distances – the 500 m and the 1,000 m – and he joined the world's sprint skating elite in 1965...
   
   
3. Hans Lichtenstern
4. Monika Pflug
   Monika Pflug
   Monika Pflug , also known as Monika Holzner-Pflug and Monika Gawenus-Pflug, is a former speed skater from Germany. She was born in Munich and competed for West Germany....
   
   
5. Herbert Schwarz
6. Monika Stützle
7. Gerhard Zimmermann