1. Reference1
Dr. Donghui Fang, Associate Professor, College of Mathematics and Statistics, Jishou University, Jishou, 416000, P. R. CHINA
Email: dh_fang@163.com
2. Reference2
Prof. Debasis Sarkar, Department of Applied Mathematics, University Of Calcutta 92 A. P. C. Road, Kolkata -700 009, India.
Email: dsappmath@caluniv.ac.in; debasis1x@yahoo.co.in