1. Batschelet E (1965) Statistical methods for the analysis of problems in animal orientation and certain biological rhythms. In: Galles SR, Schmidt-Koenig K, Jacobs GJ, Belleville RF (eds) Animal orientation and navigation. Washington, NASA, pp 61?91
2. Batschelet E (1981) Circular statistics in biology. Academic Press, London
3. Benedetti PA, Lenci F (1977) In vivo microspectrofluorometry of photoreceptor pigments in Euglena gracilis. Photochem Photobiol 26:315?318
4. Checcucci A, Colombetti G, Ferrara R, Lenci F (1976) Action spectra for photoaccumulation of green and colorless Euglena: evidence for identification of receptor pigments. Photochem Photobiol 23:51?54
5. Colombetti G, Lenci F (1982) Responses to photic, chemical and mechanical stimuli. In: Buetow DE (ed) The biology of Euglena, vol III. Academic Press, New York, pp 169?195