Cerver, Francisco Asensio
Arco Editorial, [1997]
Buku Teks SO
Lewis, Lesley
David & Charles, 1980
Buku Teks SO
VSNU, 2009
Buku Teks
Gluck, Peter L.
Rockport Publishers, 1997
Buku Teks SO
Savage, Charles C.
University of Missouri Press, 1987
Buku Teks SO