Thomas, Meryl, author
Blackstone Press LTD, 2000
Buku Teks
Cunningham, Roger A., author
West Pub., 1993
Buku Teks
Smith, Roger J., author
Longman, 2000
Buku Teks
Megarry, Robert, author
Stevens and Sons, 1975.
Buku Teks
M. Hawin, author
Gadjah Mada University Press, 2010
Buku Teks