1. Akehurst, S.C. 1931. Observations on pond life.J. R. Microsc. Soc. London 51:236?265.
2. Carefoot, J.R. 1968. Culture and heterotrophy of the freshwater dinoflagellatePeridinium cinctum fa.ovoplanum Lindemann.J. Phycol. 4:129?131.
3. Harder, R. 1917. Ernahrungsphysiologische Untersuchungen an Cyanophyceen, hauptsachlich dem endophytischenNostoc punctiforme.Z. Bot. 9:145?242.
4. Harris, D.O. 1971a. Growth inhibitors produced by the green algae (Volvocaceae).Arch. Mikrobiol. 76:46?50.
5. Harris, D.O. 1971b. A model system for the study of algae growth inhibitors.Arch. Protistenk. 113:230?234.