The Cetaceans Phocoena phocoena and Tursiops trunctatus in the Marsdiep area (Dutch Wadden Sea) in the years 1931-1973 . Part I
Verwey, J. (1975). The Cetaceans Phocoena phocoena and Tursiops trunctatus in the Marsdiep area (Dutch Wadden Sea) in the years 1931-1973 . Part I. NIOZ-rapport, 1975(17a). Nederlands Instituut voor Onderzoek der Zee: Texel. 98 pp.
Part of: NIOZ-rapport. Netherlands Institute for Sea Research (NIOZ): Den Burg. ISSN 0923-3210