Affiliation: | 1. Ahi Evran University, Department of Mathematics, Kirsehir, Turkey;2. Institute of Mathematics and Mechanics, Academy of Sciences of Azerbaijan, F. Agayev St. 9, Baku, AZ 1141, Azerbaijan;3. Baku State Univ., Dept. Math. Anal., Baku, AZ 1141, Azerbaijan;4. Dipartimento di Matematica, Università di Catania, Viale A. Doria, 6, 95125 Catania, Italy |