Deanna B. Marcum, editor
Greenwood Press, 2001
Buku Teks SO
Pierce, Eleanor B.
Pan American Airways, 1965
Buku Teks SO
Artikel Jurnal
edited by Richard A. Danner and Marie-Louise H. Bernal
Oceana Publications, 1994
Buku Teks SO
Losonsky, Michael
Cambridge University Press, 2006
Buku Teks SO