Benham, Frederic
New York, N.Y. Pitman 1947,
Buku Teks
Benham, Fredeic
Sir Isaac Pitman & Sons, 1960
Buku Teks
Benham, Frederic
Pitman Publishing Corporation, 1941
Buku Klasik
Case, Karl E., author
Pearson, Prentice Hall, 2009
Buku Teks
Mankiw, N. Gregory, author
Harcout College, 1998
Buku Teks