Text and Data Mining valid from 2018-09-10
Received: 21 January 2018
Accepted: 29 August 2018
First Online: 10 September 2018
Ethics approval and consent to participate
: This study was approved by the Research Ethics Committee of Kowloon Central/ Kowloon East cluster, Hong Kong (Reference number: KC/KE-16-0218/ER-1).
: No individual person’s data was presented in this study.
: The authors declare that they have no competing interests.
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