About this article
Published Online: Jan 30, 2018
Page range: 77 - 90
Received: Nov 27, 2015
Accepted: Jan 10, 2017
DOI: https://doi.org/10.1515/udt-2017-0016
Keywords
© 2018
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
Sanna, Carlo
Department of Mathematics Università degli Studi di Torino, Torino,Via Carlo Alberto, ITALY