Leslie, Douglas L., author
West Publishing, 1992
Buku Teks
Champion, Walter T, author
WEST , 2009
Buku Teks
Pearson, Michael W., author
Pearson education, 2015
Buku Teks
Michael S. Schumann ... [and others]
Van Nostrand Reinhold , 1996
Buku Teks
Bigelow, Robert P., author
Upper Saddle River, NJ: Prentice Hall, 1975,
Buku Referensi