Jarvis, Peter J.
Prentice-Hall, 2000
Buku Teks SO
edited by S.E. Jorgensen, B. Halling-Sorensen, S.N. Nielsen
Lewis Publishers, 1996
Buku Referensi
Withers, Philip C.
Oxford University Press, 2016
eBooks
edited by J. Rozema and J.A.C. Verkleij
Kluwer Academic, 1991
Buku Teks SO
Plumwood, Val
Routledge, 2002
Buku Teks