Leite, Paulo Roberto de Miranda, et al. “Factors Influencing Gestation Length and Calving Interval of Gir Cows under Northeast Brazil Conditions”. Pesquisa Agropecuaria Brasileira, vol. 21, no. 1, Apr. 2014, pp. 87-92, doi:10.1590/S1678-3921.pab1986.v21.14664.