Syväoja, E.-L., and M. Kreula. “Incorporation of Radioactive Carbon from [14C] Alanine in the Rumen of a Cow Given Feed Containing Urea As the Sole Source of Nitrogen”. Agricultural and Food Science, vol. 52, no. 1, Jan. 1980, pp. 69-74, doi:10.23986/afsci.72032.