Team, S. “On the Least (Ordered) Semilattice Congruence in Ordered $\Gamma$-Semigroups: M. Siripitukdet, A. Iampan”. Thai Journal of Mathematics, vol. 4, no. 2, Dec. 2006, pp. 403-15, https://thaijmath2.in.cmu.ac.th/index.php/thaijmath/article/view/60.