Lekdee, Natchapon http://orcid.org/0000-0001-6751-7555
Sirisubtawee, Sekson http://orcid.org/0000-0003-0715-470X
Koonprasert, Sanoe http://orcid.org/0000-0001-5236-033X
Funding for this research was provided by:
Centre of Excellence in Mathematics, Thailand
Article History
Received: 4 February 2019
Accepted: 25 July 2019
First Online: 6 August 2019
Competing interests
: The authors declare that they have no competing interests.