by Swift, R.W., Barron, G.P., Fisher, K.H., French, C.E., Hartsook, E.W., Hershberger, T.V., Keck, E., Long, T.A., Magruder, N.D.
Published in The Journal of nutrition (01.05.1958)

by Magruder, N.D., Bletner, J.K., Clark, T.B., Weakley, C.E.
Published in Poultry science (01.05.1954)

by SWIFT, R W, BARRON, G P, FISHER, K H, FRENCH, C E, HARTSOOK, E W, HERSHBERGER, T V, KECK, E, LONG, T A, MAGRUDER, N D
Published in The Journal of nutrition (10.05.1958)