1. School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal; Pietermaritzburg South Africa
2. Department of Mathematics; A. K. P. C. Mahavidyalaya; Hooghly India
3. Department of Mathematics; Amity University; Kolkata, Newtown India
4. School of Education, University of KwaZulu-Natal; Pinetown South Africa