Dee ihe na-aga n'ihu maka paragraf a - Margretta "Gretta" Kok (amụrụ 16 Ọktoba 1944, na Amsterdam) bụ onye na-egwu mmiri Dutch lara ezumike nká nke sonyere na 1960 na 1964 Summer Olympics. N'afọ 1960, ọ bụ onye nke ise n'asọmpi 200m breaststroke, ebe n'afọ 1964 ọ erubeghị asọmpi ikpeazụ. N'afọ 1966, o nwetara ihe nrite ọla edo na 4 × 100 m medley relay na European Aquatics Championships
Ọ dị mma. Nwanne ya nwanyị nke nta, Ada Kok, bụkwa onye na-egwu mmiri n'egwuregwu Olympic ma bụrụ akụkụ nke otu ìgwè ahụ meriri ọlaedo medley na 1966.