Silva, Antônio Emidio Dias Feliciano, et al. “Seasonal Sexual Activity of Nellore Bulls and Their Cross-Breed With Fleckvieh and Chianina: Biometric Testicular Characteristics”. Pesquisa Agropecuaria Brasileira, vol. 26, no. 10, Oct. 1991, pp. 1745-50, doi:10.1590/S1678-3921.pab1991.v26.3521.