Text and Data Mining valid from 2019-02-22
Received: 4 September 2018
Accepted: 13 February 2019
First Online: 22 February 2019
Ethics approval and consent to participate
: The study was performed in accordance with the declaration of Helsinki and approved by the Ethics Committee of Bielefeld University. All participants signed an informed consent form.
: Not applicable.
: The authors declare that they have no competing interests.
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