Artikel Jurnal
Harrower, Elizabeth, 1928-
Angus & Robertson, 1958
Buku Teks
Artikel Jurnal
edited by Preston E. James and Clarence F. Jones
Syracuse University Press, 1967
Buku Teks SO
edited by Vincent Shen, Kwong-loi Shun
The Council for Research in Values and Philosophy, 2008
Buku Teks SO