Funding for this research was provided by:
Christian Doppler Forschungsgesellschaft
Text and Data Mining valid from 2018-03-14
Received: 9 August 2017
Accepted: 23 February 2018
First Online: 14 March 2018
: The author declares that he has no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.