Rojas, Carlos, author
London : Harvard University Press, 2010
Buku Teks
Parents' Magazine's Cultural Institute, 1965
Buku Referensi
Turner, Ralph, author
McGraw-Hill, 1941
Buku Teks
Gilman, Sander L., author
Polity Press, 2008
Buku Teks
Mohammed Ali
Punjab Eductional Press, 1964
Buku Teks