Steers, Richard M., author
Kent Publishing, 1985
Buku Teks
Higgins, James M., author
Macmillan, 1994
Buku Teks
Taylor, Bernard W., III, author
Pearson Education, 2004
Buku Teks
Lockyer, K.G., author
Sir Isaac Pitman and Sons, 1969
Buku Teks
This, Leslie E.
Adison Wesley Publishing, 1974
Buku Teks