1. Department of Mathematics, Pan African university for Basic Science, Technology and Invocation (PAUSTI) /JKUAT, Nairobi, Kenya
2. Department of Applied Mathematics, Debre Markos University, Debre Markos, Ethiopia
3. Department of Pure and Applied Mathematics, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
4. School of Public Health, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya