na INLIS000000000024907 Ind 0010-1218006745 An illustrated guide to ciliated protozoa used as biological indicators in freshwater ecology BICK, Hartmut Hartmut Bick [s.l.] WHO 1969 20 p. : ill. ; 28 cm. 20 p. : ill. ; 28 cm. 593.1BICi 593.1 CILIOPHORA FRESHWATER ECOLOGY mfn-26762