Wright, Elizabeth, 1926-2000
Routledge, 1984
Buku Teks SO
Dieter Lohmar
Springer Science, 2012
eBooks
Trias Melia
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 2013
UI - Skripsi Membership
Holland, Norman Norwood
Oxford Universiy Press, 1990
Buku Referensi
Pines, Dinora
Viargo, 1993
Buku Teks SO