Victoria University of Washington, 1982
Buku Teks
by Victoria Fromkin ... [and others]
Holt, Rinehart and Winston, 1990
Buku Teks SO
edited by Ajaya Kumar Gupta
American Society of civil engineering, 1981
Buku Teks SO
Edwards, Heather M., 1947-
Scarecrow Press, 1990
Buku Teks SO
Artikel Jurnal