Lindeman, Ralph D
Twayne Publishing, 1965
Buku Teks
[Canberra] Angus & Robertson 1989,
Buku Referensi
Greenlees, Duncan
The Theosophical Publishing House, 1952
Buku Teks
Norman, Donald A
Basic Book, 2004
Buku Teks
Stewart, Ian
Chapman & Hall, 1992
Buku Teks