Affiliation: | 1. College of Science, Northwest A&F University, Yangling 712100, Shaanxi, People''s Republic of China;2. Department of Mathematics, East China Normal University, 500 Dongchuan Road, Shanghai 200241, People''s Republic of China;1. Faculty of Computers and Informatics, Zagazig University, Zagazig, Egypt;2. Department of Mathematics, Qassim University, Saudi Arabia;3. Department of Statistical Science, Southern Methodist University, Dallas, TX 75275-0332, USA |