1. Bünning E (1973) The physiological clock. Circadian rhythms and biological chronometry. Springer, Berlin Heidelberg New York
2. Engelmann W, Klemke W (1983) Biorhythmen. Quelle und Meyer, Heidelberg
3. Haupt W (1977) Bewegungsphysiologie der Pflanzen. Thieme, Stuttgart
4. Sweeney BM (1987) Rhythmic phenomena in plants. 2. edn. Academic Press, New York
5. Vince-Prue D, Thomas B, Cockshull KE (eds) (1984) Light and the flowering process. Academic Press, London