Fristrup B. Ice Alias of the Northern Hemisphere. Hydrographie Office, publication no. 550. Udgivet af Hydrographie Office, United States Navy under the authority of the Secretary of the Navy. Washington. gt [Internet]. 1. januar 1950 [henvist 5. december 2025];50. Tilgængelig hos: https://tidsskrift.dk/geografisktidsskrift/article/view/48456