9George A P. Effeet of the time of application of fertilizer nitrogen on the growth, flowering and fruiting of Maiden apple trees grown in sand culture[J]. Scientia Horticulturae, 1992,49(3) : 197-207.
10Grozov D N, Shishkanu G V. Photosynthesis by apple trees on a dwarfing rootstoek Sadovodstvo [J].Vinogradarstvo Vinodelie Mol- davii, 1972, (12) : 10-13.