Dr. Hasibun Naher, Lecturer in Mathematics, Department of Mathematics and Natural Sciences, BRAC University, 66 Mohakhali, Dhaka-1212, Bangladesh
E-mail: hasibun06tasauf@gmail.com; hasi@bracu.ac.bd

Dr. V. Ananthaswamy, Assistant Professor, Department of Mathematics, The Madura College (Autonomous), Madurai, Tamil Nadu, India
E-mail: ananthu9777@gmail.com