Frieden, Jeffry A., author
Thomson Wadsworth, 2000
Buku Teks
Smith, Adam, author
Modern Library, 2000
Buku Teks
Smith, Adam, author
David Campbell Publishers, 1991
Buku Referensi
Smith, Adam, author
Modern Library, 1937
Buku Referensi
Daughterty, Caroll R., author
Houghton Mifflin, 1950
Buku Teks