Ferreira, A. da M., Salomoni, E. and Del Duca, L.O.A. (1991) “Effects of year, weight gain, breeding season and sex of calf on the conception rate of primiparou cows”, Pesquisa Agropecuaria Brasileira, 26(8), pp. 1165–1174. doi:10.1590/S1678-3921.pab1991.v26.3453.