Text and Data Mining valid from 2018-07-19
Received: 22 August 2017
Accepted: 25 June 2018
First Online: 19 July 2018
Ethics approval and consent to participate
: The study was evaluated and approved by the local authority (Regierung von Oberbayern, approval no. 55.2–1–54-2531-17-10) as required by German law.
: Not applicable.
: The authors declare that they have no competing interests.
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