Text and Data Mining valid from 2017-09-01
Received: 17 January 2017
Accepted: 1 August 2017
First Online: 1 September 2017
Ethics approval and consent to participate
: The analysis was performed with the permission of the local ethics committee of the Ludwig-Maximilians University of Munich (reference number 150–14).
: Not applicable.
: The authors declare that they have no competing interests.
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