Text and Data Mining valid from 2019-02-19
Received: 1 November 2018
Revised: 12 December 2018
Accepted: 12 December 2018
First Online: 19 February 2019
: The author declares no competing interests.
: This work is published under the standard license to publish agreement. After 12 months the work will become freely available and the license terms will switch to a Creative Commons Attribution 4.0 International (CC BY 4.0).