Kent, Sherman
Appleton Century Croffs, 1967
Buku Teks
Kent, Sherman
Appleton Century Croffs, 1941
Buku Teks
Kraus, Michael
University of Oklahoma Press, 1953
Buku Teks
Bowman, Francis J
Iowa W.M.C. Brown, 1951
Buku Teks
Thompson, James Westfall
Macmillan, 1958
Buku Teks