Nielsen, Niels. “Olaf Holtedahl: The Submarine Relief off the Norwegian Coast. 41 S. (18 X 27 cm), Oslo 1940”. Geografisk Tidsskrift - Danish Journal of Geography 45 (January 1, 1942). Accessed December 5, 2025. https://tidsskrift.dk/geografisktidsskrift/article/view/48329.