5HARTMANN C, JOHANSSON K, STRANDBERG E, et al. One-generation divergent selection on large and small yolk pro- portions in a white Leghorn line [J]. British Poultry Science, 2000,41 (3) : 280-286.
6SCOTY T A, SILVERSIDES F G. The effect of storage and strain of hen on egg quality[J]. Poultry Science,2000,79(12): 1725-1729.