- Author: Leffler William L., Ormston Susan E., Womack Karla
- Language: English
- Year: 2014
- Author: Burdick Donald L., Leffler William L.
- Year: 2010
- Author: Leffler William L.
- Language: English
- Year: 2008
- Author: Leffler William L.
- Language: English
- Year: 2008