Gallwey, Timothy Josep
CRC Press, Taylor & Francis Group, 2009
Buku Teks
Sousa, John J.
Rhode Island Consortium, 1990
Buku Teks
Leith, John D.
Burgess, 1970
Buku Teks
edited by Bruce W. Burkhart and Wesley S. Thompson
Burgess Publishing, 1972
Buku Teks
Mertens, Thomas R.
Burgess, 1968
Buku Teks