Smith, Elton Edward
Twayne Publishers, 1965
Buku Teks
Volpe, Edmond L.
The Nooday Press , 1964
Koleksi Publik
Clarke, D. Waldo, author
Longmans, Green, 1950
Buku Teks
Wilson, Phillip, author
Twayne Publishers, 1968
Buku Teks
Nelson, James G., author
Twayne, 1966
Buku Teks