591.98 Del P Delta Institute for Hydrobiological Research Progress Report 1978. Edited by E. K. Duursma. Yerseke [1979?] 128-231 p. ilus. 26 cm. "Reprinted from "Institutes of the Royal Netherlands Academy of Arts and Sciences, Progress. Report 1978; Verhandelingen der Koninklijke Nederlandse Akademie van Wetensenschappen, Afdeling Natuurkunde, Tweede Reeks deel 73 (1979)