1. Department of Mathematics and Applied Mathematics, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, Medunsa, South Africa
2. Department of Mathematics and Applied Mathematics, Sefako Makgatho Health Sciences University, Ga-Rankuwa, Pretoria, Medunsa, South Africa + Quantum Leap Africa (QLA), AIMS Rwanda Centre, Remera Sector, Kigali, Rwanda + African Center for Advanced Studies (ACAS), Yaoundé, Cameroon
3. Department of Mathematics, Faculty of Science, Atatürk University, Erzurum, Turkey