E.J. Akpabio, E.J. Ekott and M.E. Akpan
Environmental Research Journal 5 ( 2 ): 59 - 65 , 2011
C. Ijogbemeye Oseghale, E.J. Akpabio and O. Edebor
Journal of Engineering and Applied Sciences 7 ( 4 ): 348 - 352 , 2012