Jarvis, Peter J.
Prentice-Hall, 2000
Buku Teks
edited by J. Rozema and J.A.C. Verkleij
Kluwer Academic , 1991
Buku Teks
edited by S.E. Jorgensen, B. Halling-Sorensen, S.N. Nielsen
Lewis Publishers, 1996
Buku Referensi
Young, J.Z.
Clarendon Press, 1975
Buku Teks
Plumwood, Val
Routledge, 2002
Buku Teks