- Author: Neba Ndenecho
- Language: English
- Year: 2011
- Author: Stanley D. Brunn, Stanley W. Toops, Richard Gilbreath
- Language: English
- Year: 2012
- Author: Joshua Bolchover, John Lin
- Language: English
- Year: 2013
- Author: Horace Campbell
- Language: English
- Year: 2013
- Author: World Bank
- Language: English
- Year: 2013
- Author: George Ngwane
- Language: English
- Year: 2008
- Author: Peterkins Manyong
- Language: English
- Year: 2008
- Author: Ivor Ludlam
- Language: English
- Year: 2014
- Author: Zubair K. Bhatti, Jody Zall Kusek, Tony Verheijen
- Language: English
- Year: 2014