Rowe, Alan J., author
Macmillan, 1992
Buku Teks
by Jefferson P. Jones ... [and others]
South-Western Cengage Learning, 2012
Buku Teks
Hague, D.C., author
Longman, 1971
Buku Teks
Mattel, Bruce, author
John Wiley & Sons, 2008
Buku Teks
Munter, Mary, author
Prentice-Hall, 1982
Buku Referensi