Durán López, M. E., Z. Barrientos Llosa, and C. Charpentier Esquivel. “Environmental Perception by Urban School Children: Influence of Green Areas, Financing and Sex in Costa Rica”. UNED Research Journal, vol. 8, no. 1, June 2016, pp. 31-39, doi:10.22458/urj.v8i1.1220.