La Rose
Alam Budaya, 1990
Buku Teks
Gillespie, Sheena
Allyn and Bacon , 1994
Buku Teks
Schneider, Susan C.
Prentice-Hall, 1997
Buku Teks
Helaine Selin
Springer Science, 2012
eBooks
edited by Chibueze C. Udeani ... [et al.]
Council for Research in Values and Philosophy,, 2006
Buku Teks