Funding for this research was provided by:
Universidad Nacional Autónoma de México (UNAM-FQ-PAIP 5000-9171)
Text and Data Mining valid from 2018-10-04
Received: 29 June 2018
Accepted: 25 September 2018
First Online: 4 October 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.