Funding for this research was provided by:
Text and Data Mining valid from 2019-07-29
Received: 18 April 2019
Accepted: 24 July 2019
First Online: 29 July 2019
Ethics approval and consent to participate
: No primary data were collected for this study; therefore, no further institutional review board approval was sought.
: Not applicable.
: The authors declare that they have no competing interests.