1. HABER, A. H. and TOLBERT, N. E. (1959). Effect of gibberellic acid, kinetin and light on the germination of lettuce seed. In:Photoperiodism and related phenomena in plants and animals, (Ed. R. B. Withrow) 197–206. American Association for the Advancement of Science, Washington D.C.
2. HEYDECKER, W. (1967). Critical factors in the germination of non-dormant seeds. In:Physiology, ecology and biochemistry of germination, (Ed. H. Borriss), 65–78. E.M. Arndt-Universität, Greifswald.