@book{68934,
	author = {Ferreiro, Emilia. and Teberosky, Ana.},
	title = {Los sistemas de escritura en el desarrollo del niño /},
	publisher = {Siglo Veintiuno Editores,},
	year = {2007.},
	address = {México, D.F. :},
	edition = {23a ed.}
}