Ricardo Viveros, James, et al. “The Health and Work Conditions of Informal Traders Marketplaces of Popayán, Colombia”. Revista Colombiana De Salud Ocupacional, vol. 2, no. 3, Sept. 2012, pp. 5-12, https://revistas.unilibre.edu.co/index.php/rc_salud_ocupa/article/view/4837.