Funding for this research was provided by:
National Institute on Drug Abuse (K01DA031745, DA042029, DA015222, DA018343)
Text and Data Mining valid from 2018-11-08
Received: 25 July 2018
Accepted: 4 October 2018
First Online: 8 November 2018
Compliance with ethical standards
: The authors declare that there is no conflict of interest.