F.A. Danjuma, E.K. Bawa, A.I. Nwannenna, and T. Aluwong. “Prostaglandin Versus Progestagen Protocols in Oestrus Synchronization in the Yankasa Ewe”. Scientific Journal of Animal Science, vol. 4, no. 9, Sept. 2015, pp. 97-102, http://sjournals.com/index.php/sjas/article/view/235.