1. 1. Abe, K., Ishibashi, K., Ohmae, M., Kawabe, Y. and Katsui, G. 1977. Determination of vitamin A in serum and liver by high-speed liquid chromatography. Vitamins 51: 275–280 (in Japanese with English abstract).
2. 2. Akashi, F., Oda, Y., Kojima, S., Yoshizawa, S., Shimizu, I., Tomonaga, S., Funaba, M. and Matsui, T. 2016. The relationship between the incidence of bumble foot and plasma vitamin A, vitamin E and zinc concentrations in captured African penguins (Spheniscus demersus). Trace Nutr. Res. 33: 73–79 (in Japanese with English abstract).
3. 3. Alvarenga, R., Zangeronimo, M., Pereira, L., Rodrigues, P. and Gomide, E. 2011. Lipoprotein metabolism in poultry. Worlds Poult. Sci. J. 67: 431–440.
4. 5. Bernard, J., Calle, P. and Ullrey, D. 1989. Extraordinary dietary vitamin A and D levels in rockhopper penguins (Eudyptes cresfutus). pp. 105–107. In: Annual Proceedings −American Association of Zoo Veterinarians, Greensboro.
5. 6. Braekkan, O. R., Ingebrigtsen, O. and Myklestad, H. 1969. Uptake and storage of vitamin A in rainbow trout (Salmo gairdneri). Int. Z. Vitaminforsch. 39: 123–130.