John Wiley & Sons, 1977
Buku Teks
edited by Richard Feachem, Michael McGarry, Duncan Mara
John Wiley & Sons, 1980
Buku Teks
Cairncross, Sandy, author
John Wiley & Sons, 1993
Buku Teks
Mara, D. Duncan (David Duncan), 1944-, author
John Wliley & Sons , 1983
Buku Teks
Eddleston, Michael
New York Oxford Univ. Press 2002,
Buku Referensi