Taylor, Julie D., author
Rockport Publishers, 2002
Buku Teks SO
Asensio, Paco, editor
Loft, 2002
Buku Referensi
Taylor, Andrew, author
University of Queensland Press, 1971
Buku Teks
Brush, Don O., author
McGraw-Hill, 1975
Buku Teks
Gjelsvik, Atle, author
John Wiley & Sons, 1981
Buku Teks