McLaughlin, Andrew C., author
Appleton Century Crofts, 1935
Buku Teks
Alden, John Richard, author
American Book Company, 1960
Buku Teks
Clark, Victor S., author
Carnegie Institution of Washington, 1949
Buku Teks
Hook, Sidney, author
University of Nebraska Press , 1967
Buku Teks
Doy, Clemens, author
1991
UI - Tesis (Membership)