Text and Data Mining valid from 2019-04-10
Received: 19 December 2018
Accepted: 7 March 2019
First Online: 10 April 2019
Ethics approval and consent to participate
: The study was approved by the local Committee on Bioethics of the School of Public Health of al-Farabi Kazakh National University.
: Not applicable.
: The authors declare that they have no competing interests.
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