editor, Paco Asensio.
Harper Collins, 2003.
Buku Teks SO
Landis, Dylan
PBC International, 1996
Buku Referensi
Alpern, Andrew
McGraw-Hill, 1975
Buku Teks SO
edited by Mildred F. Schmertz
McGraw-Hill, 1981
Buku Teks SO
Mario Teguh
Progressio, 2006
Buku Teks