1. Bukovac MJ, Hull J, Kesner CD, Larsen RP (1987) Mich State Hortic Soc 116:122
2. Coggins CW, Lewis LN (1965) Proc Am Soc Hortic Sci 86:272
3. Creasy LL, Swartz HJ (1981) J Am Soc Hortic Sci 106:203
4. Dunand RT (1987) Proc Plant Growth Regul Soc Am 14:485
5. Dyer D, Carlson DR, Cotterman CD, Sikorski JA (1986) Proc Plant Growth Regul Soc Am 13:130