Andreatta, Susan, author
Wadsworth, Cengage Learning, 2013
Buku Teks
Williams, Thomas Rhys
Holt, Rinehart and Winston, 1967
Buku Teks
Kaplan, David, author
Pustaka Pelajar, 2012
Buku Teks
Birket-Smith, Kaj, author
University of Wisconsin Press, 1965
Buku Teks
Peters-Golden, Holly, author
McGraw-Hill, 2012
Buku Teks