Funding for this research was provided by:
Ministerio de Economía y Competitividad (MAT2013-48624-C2-1-P, BIA2015-63882-P)
Text and Data Mining valid from 2018-06-05
Received: 9 May 2018
Accepted: 21 May 2018
First Online: 5 June 2018
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.