Barbosa, R.T., Esper, C.R. and de Freitas, A.R. (1998) “Midpiece length of bovine spermatozoa and its relationships to semen traits and fertility”, Pesquisa Agropecuaria Brasileira, 33(10), pp. 1661–1665. doi:10.1590/S1678-3921.pab1998.v33.4991.