- Author: Andrew Spencer Robert Henley
- Language: English
- Year: 2013
- Author: Elizabeth DuPont Spencer Robert L. DuPont Caroline M. DuPont
- Language: English
- Year: 2003
- Author: Elizabeth DuPont Spencer Robert L. DuPont Caroline M. DuPont
- Language: English
- Year: 2003
- Author: Roger Spencer Robert Cross Peter Lumley
- Language: English
- Year: 2007