Madureira, E.H. (1990) “Progesterone concentrations measured by radioimmunoassay in blood plasma and in fat-free milk of Gir breed cows iBos indicus). Determinations during oestrus cycle. Early pregnancy diagnosis”., Brazilian Journal of Veterinary Research and Animal Science, 27(2), pp. 247–253. doi:10.11606/issn.0000-0000.272247-253.