Neto, J. de S., Baker, G. A. and de Sousa, F. B. (1995) “Socioeconomical analysis of goats and sheep exploitation in Piauí State, Brazil”, Pesquisa Agropecuaria Brasileira, 30(8), pp. 1017–1030. doi: 10.1590/S1678-3921.pab1995.v30.4392.