7Mason W L. Vegetative propagation of hybrid Larch Using Winter Cuttings [ J ]. Forestry Supplement, 1989,62:189 -198.
8STEWART R N. Somatic gentic analysis of the apical layers of chimeral sports in chrysanthemum by experi mental production of adventitious shoots [ J ]. Amer Jour Botany, 1970,57 : 1061 - 1071.