Silveira, P. R. S. da, Wentz, I. and Freitas, A. R. de (2014) “Reproductive performance of sows inseminated once or twice using semen stored in kiew extender”, Pesquisa Agropecuaria Brasileira, 19(7), pp. 909–913. doi: 10.1590/S1678-3921.pab1984.v19.15972.