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2. The Roche yolk colour fan;Anonymous,1965
3. Recommended standards for scoring and measuring opened egg quality;Brant;Food Technology,,1951
4. The influence of energy source, energy-fiber concentration and protein source of the diet on certain egg quality characteristics;Mueller;Poultry Sci.,1956
5. Yolk color and candled grade of eggs;Mueller;Pennsylvania Agr. Exp. Sta. Progr. Rpt.,1957