B. Hasin, A. Ferdaus, M. Islam, M. Uddin, and M. Islam, “Marigold and Orange Skin as Egg Yolk Color Promoting Agents”, Int. J. Poult. Sci., vol. 5, no. 10, pp. 979–987, Sep. 2006, doi: 10.3923/ijps.2006.979.987.