Text and Data Mining valid from 2018-01-05
Received: 19 October 2017
Accepted: 2 November 2017
First Online: 5 January 2018
Change Date: 23 October 2019
Change Type: Correction
Change Details: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Compliance with ethical standards
: The authors declare that they have no conflict of interest.