Coba jelasin Lihat juga dari Kapal selam tipe XXI dong

Daftar Kapal Selam Tipe XXI

Fitzsimons, Bernard, general editor. The Encyclopedia of 20th Century Weapons and Warfare (London: Phoebus Publishing Company, 1978), Volume 24, p. 2594, "'Whiskey'", and p. 2620, "'Zulu'".