editor, Frederick G. Ruffner, Robert C. Thomas, Ann Underwood, Harold C. Young
Gale Research, 1964
Buku Referensi
Grolier Incorporated, 1964
Buku Referensi
Fincher, E. B., author
Abelard-Schuman, 1955
Buku Teks
by A. F. Gustafson [and others]
Comstock Publishing Associates, 1961
Buku Teks
Myers, Gustavus, author
Random House, 1943
Buku Teks