Text and Data Mining valid from 2018-03-26
Received: 24 August 2016
Revised: 24 December 2017
Accepted: 14 March 2018
First Online: 26 March 2018
Compliance with ethical standards
: There have been no involvements that might raise the question of bias in the work reported or in the conclusions, implications or opinions stated. The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.