Paulo Freire, La educación como práctica de la libertad, Siglo veintiuno editors: Mexico, 1967 and Pedagogy of the Oppressed, Trans. Myra Bergman Ramos, Seabury Press: New York, 1970.

See also Paulo Freire and Antonio Faundez, Learning to Question: A Pedagogy of Liberation, Trans. Tony Coates, WCC Publications: Geneva, 1989.