Toniollo, G.H. (1998) “Progesterone -17alpha -OH and androstenediona serum levels evaluation during the oestrus cycle in guilts (Sus Scrofa Domestica - Linnaeus, 1758)”, Brazilian Journal of Veterinary Research and Animal Science, 35(5), pp. 205–209. doi:10.1590/S1413-95961998000500002.