1. Galston, A. W., andW. S. Hillman, in: Encyclopedia of Plant Physiology, ed. byW. Ruilland, vol XIV, p. 647?670. Berlin- G�ttingen-Heidelberg: Springer 1961.
2. Stutz, R. E. Plant Physiol.32, 31 (1957).
3. Troll, H.-J.: Z�chter28, 25 (1958).
4. Tang, Y. W., andJ. Bonner: Am. J. Bot.35, 574 (1948).
5. Galston, A. W., in: Photoperiodism and related phenomena in plants and animals, p. 137?157. Washington: AAAS 1959