Zoo Duisburg

#1961 (1st ed.) 

1970 (3rd ed.) 

1971 (4th ed.) 

1972 (5th ed.) 

1973 (6th ed.) 

1974 (7th ed.) 

1975 (8th ed.) 

1976 (9th ed.) 

1977 (10th ed.) 

1979 (11th ed.) 

1980 (12th ed.) 

1981 (13th ed.) 

1984 (14th ed.) 

1986 (15th ed.) 

1988 (16th ed.) 

1990 (17th ed.) 

1991 (18th ed.) 

1992 (19th ed.) 

1994 (20th ed.) 

#2014

ca.1985

1994