Walls, Alfonso Vasseur
Mexico Diana S.A. 1963
Buku Referensi
Cadena, Mariano Velazquez de la
Follett, 1962
Buku Referensi
Fucilla, Joseph G.
Follett Publishing Company, 1964
Buku Referensi
Eckersley, C. E. (Charles Ewart), 1892-1967
Longmans, Green and Co., 1953
Buku Referensi
London; Cassell LTD., 1978
Buku Referensi