Funding for this research was provided by:
FP7 Socio-Economic Sciences and Humanities (613468)
Ministerio de Economía, Industria y Competitividad, Gobierno de España (CSO2014-59927-R)
Text and Data Mining valid from 2019-09-14
Received: 25 October 2018
Accepted: 15 July 2019
First Online: 14 September 2019
: Not applicable (authors declare that they have no competing interests).