About this article
Published Online: Mar 04, 2019
Page range: 242 - 248
Received: Jul 06, 2017
DOI: https://doi.org/10.2478/ausm-2018-0019
Keywords
© 2018 C. Carpintero et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
The aim of this paper is to introduce and study upper and lower