Text and Data Mining valid from 2019-05-16
Received: 28 December 2018
Accepted: 30 April 2019
First Online: 16 May 2019
Ethics approval and consent to participate
: The study methods were submitted and approved by the Institutional Ethics Committee of Riga Stradins University. This study was conducted in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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