1. Altenburg, E.: Amer. Naturalist80, 359–367 (1946);81, 72–76 (1947).
2. Aakerman, S.: Hereditas2, 90–112 (1921).
3. Brücher, H.: Z. Vererbgsl.75, 298–340 (1938);77, 455–487 (1939); Flora N. F.34, 215–228 (1940); Jb. wiss. Bot.91, 331–351 (1943).
4. Chittenden undPellew, Nature119 (1927).
5. Cleland, R. E.: Proc. Amer. Philos. Soc.77, 477–542 (1937).