na INLIS000000000023506 Ind 0010-1218005344 Productivity problems of freshwaters: proceedings of the IBP-UNESCO symposium on productivity prolems of freshwaters hel in Kazimiers Dolny, Polond, May 6-12, 1970 SYMPOSIUM ON PRODUCTIVITY PROBLEMS OF FRESHWATERS (1970 : Kazimiers Dolny) Editors Z. Kajak; A. Hillbricth-Ilkowska Warsawa Polish Scientific 1972 918 p. : ill. ; 24 cm. 918 p. : ill. ; 24 cm. 639.6SYMp 639.6 FRESHWATER ECOLOGY 503/74 1149/79