http://reply.papertrans.cn/1/9/875/875-31.png
Submitted on: 18 June 2009.
Revised on: 07 September 2009.
Accepted on: 08 October 2009.
___________________Africa Spectrum---SAGE PUBLICATIONS INC
http://reply.papertrans.cn/1/9/875/875-33.png
http://reply.papertrans.cn/1/9/875/875-34.png
http://reply.papertrans.cn/1/9/875/875-35.png
Submitted on: 17 December 2016.
Revised on: 10 February 2017.
Accepted on: 26 March 2017.
___________________Africa Spectrum---SAGE PUBLICATIONS INC