Funding for this research was provided by:
Text and Data Mining valid from 2018-03-27
Received: 28 August 2017
Accepted: 16 March 2018
First Online: 27 March 2018
Ethics approval and consent to participate
: The Heidelberg Ethics Committee approved this study on the 9th of July 2013 (S-207/2013).
: Not applicable.
: The authors declare that they have no competing interests.
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