Nielsen, Lewis T., author
Buegess Publishing, 1967
Buku Teks
Mader, Sylvia S., author
Wm. C. Brown Publisher, 1993
Buku Teks
Beck, Raymond W., author
Burgess, 1977
Buku Teks
Burgess Publishing Company, 1969
Buku Teks
Murray, P. D. F. (Patrick Desmond Fitzgerald)
Macmillan, 1961
Buku Teks