Authors
Luminiţa Barbu
Department of Mathematics, Ovidius University of Constanta, Bdul Mamaia 124, 900527, Constanta, Romania
Cristian Enache
"Simion Stoilow" Institute of Mathematics of the Romanian Academy, 010702,, Bucharest, Romania
© 2017 Luminiţa Barbu, Cristian Enache, published by Ovidius University of Constanta
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.