A. E. de Villemor-Amaral and M. A. dos S. Machado, “ The depression index in the Zulliger Comprehensive System (ZSC) ”, Paidéia (Ribeirão Preto), vol. 21, no. 48, pp. 21–27, Apr. 2011, doi: 10.1590/S0103-863X2011000100004.