Funding for this research was provided by:
the Ministry of Education and Training of Viet Nam (B2018-TNA-59)
Text and Data Mining valid from 2019-11-15
Received: 28 May 2019
Accepted: 24 October 2019
First Online: 15 November 2019
Ethics approval and consent to participate
: Not applicable.
: All authors have provided their consent for submission of the manuscript to CBTA.
: The authors declare that they have no competing interests.