Gedes & Grosset, 2001
Buku Referensi
Houghton, John W.
Westview Press , 1991
Buku Teks
Johnson, George B., author
McGraw-Hill, Higher Education, 2008
Buku Teks
Stanier, Roger Y., author
Prentice-Hall, 1963
Buku Teks
Gregory, J. N., author
Angus & Robertson , 1966
Buku Teks