Sevast' yanova, L.A., 1974: Results of plum breeding in the Tatar ASSR. Tr Tatar NII s kh (5): 220-227
The most hardy and useful forms were obtained by crossing the best local forms among themselves and with relatively hardy varieties. Distant hybridization produced a great variety of new forms in the progeny, but a longer period was necessary for the production of economically useful forms. The more frost-resistant representatives of Prunus ussuriensis and P. nigra were not sufficiently drought resistant under Tatar conditions.