1. Hartman, F. O., and Howlett, F. S. (1954). Fruit setting of the Delicious apple. Bull. Ohio agric. Exfit. Sta.745.
2. Williams, R. R., and Child, R. D. (1963). Some preliminary observations on the development of self- and cross-pollinated flowers of blackcurrants.Ann. Refi. Long Ashton Res. Sta. for 1962, 59–64.