1. B. Rademacher, in: Handbuch der Pflanzenphysiologie, vol. 11, p. 655. Ed. W. Ruhland. Springer, Berlin 1959.
2. M. Evenari, in: Handbuch der Pflanzenphysiologie, vol. 16, p. 691. Ed. W. Ruhland, Springer, Berlin 1961.
3. T.N. Bhardwaja, A.K. Yadav and C.B. Gena, J. Bombay nat. Hist. Soc.75, 533 (1977).
4. B.D. Sharma and D.R. Bohra, Geobios, India4, 102 (1977).
5. A.K. Yadav, P. Sharma and T.N. Bhardwaja, Geobios, India5, 185 (1978).