Duong, Phan Thi Ha http://orcid.org/0000-0001-5589-9269
Funding for this research was provided by:
National Foundation for Science and Technology Development (101.99-2016.16)
Vietnam Institute for Advanced Study in Mathematics
Article History
Received: 19 August 2020
Revised: 12 December 2021
Accepted: 12 December 2021
First Online: 14 March 2022