Laysirikul, Ekkachai, 		Sawatraksa, Nares, AND 		Namnak, Chaiwat.
" Left regular and right regular elements of the semigroups of transformations restricted by an equivalence" <em>Naresuan University Journal: Science and Technology (NUJST)</em> [Online], Volume 26 Number 4 (15 November 2018)