edited by Yvonne Marshall
Routledge, 1997
Buku Teks
Cottrell, Leonard, author
World Pub., 1964
Buku Teks
Jessup, Ronald, author
Macdonald, 1968
Buku Teks
edited by Miranda J. Green
Routledge , 1997
Buku Referensi
Timothy Insoll
Routledge, 2001
Buku Teks