- Author: James Wilberding
- Language: English
- Year: 2011
- Author: Robert B. Todd
- Language: English
- Year: 2012
- Author: Charles Hagen
- Language: English
- Year: 2013
- Author: J.O. Urmson
- Language: English
- Year: 2013
- Author: J.O. Urmson
- Language: English
- Year: 2002
- Author: R.J. Hankinson
- Language: English
- Year: 2004
- Author: James Wilberding
- Language: English
- Year: 2006
- Author: J.O. Urmson
- Language: English
- Year: 1992
- Author: Pamela Huby
- Language: English
- Year: 2012
- Author: C.C.W. Taylor, Pamela M. Huby
- Language: English
- Year: 2011