Text and Data Mining valid from 2017-11-15
Received: 13 June 2017
Accepted: 31 October 2017
First Online: 15 November 2017
Change Date: 6 June 2019
Change Type: Correction
Change Details: A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
: The authors declare that they have no competing interests.