Silva, N. da and Fridman, P.C. da C. 2007. Unsicherheit in the XXI century: the teaching and the learning of reading and writing of portuguese language in Sao Paulo . Paidéia (Ribeirão Preto). 17, 36 (Apr. 2007), 57–68. DOI:https://doi.org/10.1590/S0103-863X2007000100006.