Moreira, Paulo Sérgio Andrade, et al. “Effect of Somatotropin on Hyperthrophy of Skeletal Muscle Fibers and Reproductive Precocity of Nelore Heifers”. Pesquisa Agropecuaria Brasileira, vol. 35, no. 9, Sept. 2000, pp. 1853-60, doi:10.1590/S1678-3921.pab2000.v35.5967.