edited by Egbert De Vries, Jose Medina Echavarria
UNESCO, 1967
Buku Teks SO
Echavarria, Jose Medina
New York, N.Y., Unesco
Buku Teks
Gordon, Lincoln
Harvard University Press, 1963
Buku Teks
edited by Miguel S. Wionczek
Frederick A. Praeger, 1966
Buku Teks
edited by Werner Baer and Isaac Kerstenetzky
Richard D. Irwin, 1964
Buku Teks