5Davis G L.Systematic Embryology of the Angiosperms.John Wiley and Sons,Inc.,New York,London and Sydney,1966
6Johri B M,Ambegaokar K B,Srivastava P S.Comparative embryology of angiosperms.New York:Springer-Verlag,Vol.1,1992
7Russell S D.Double fertilization.Int Rev Cytol,1992,140:357-388
8Russell S D,Rougier M,Dumas C.Organization of the early post-fertilization megagametophyte of Populus deltoides:Ultrastructure and implications for male cytoplasmic transmission.Protoplasma,1990,155:153-165
9Jensen W A,Fisher D B.Cotton embryogenesis:The entrance and discharge of the pollen tube in the embryo sac.Planta,1968,78:158-183
10Mogensen H L.Double fertilization in barley and the cytological explanation for Haploid embryo formation,embryoless caryopses,and ovule abortion.Carlsberg Res Commun,1982,47:313-354
