Affiliation: | 1. Department of Mathematics, Texas A&M University-Kingsville, Kingsville, Texas 78363-8202, United States;2. Department of Mathematics, Pedagogical University of Cracow, Podchor??ych 2, 30-084, Kraków, Poland;3. Faculty of Mathematics and Natural Sciences, University of Rzeszów, Pigonia 1, 35-959 Rzeszów, Poland |