1. Department of Mathematics and Statistics, University of Lahore, Lahore 54590, Pakistan
2. Key Laboratory of Syentheitc and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry and Materials Science, Northwest University, Xi'an 710127, China
3. Art and Science Faculty, Department of Mathematics, Siirt University, Siirt 56100, Turkey
4. Department of Mathematics, Çankaya University, Etimesgut, Ankara 06790, Turkey; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 406040, Taiwan