About this article
Published Online: Feb 11, 2018
Page range: 3 - 6
Received: Dec 14, 2017
Accepted: Dec 20, 2017
DOI: https://doi.org/10.2478/gp-2018-0004
Keywords
© 2018 Reinhard Heun, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Heun, Reinhard
University of BonnBonn, Germany