Canning, Joseph
Routledge, 1996
Buku Teks SO
Sabine, George H.
Harcourt Brace College Publishers, 1973
Buku Teks SO
edited by Gordon Greenwood
Angus and Robertson, 1955
Buku Teks SO
McInnis, Edgar
Clarke Irwin, 1956
Buku Teks SO
edited by Gordon Greenwood
Angus and Robertson, 1969
Buku Teks SO