Congruences on monoids of transformations preserving the orientation of a finite chain." *J. Algebra*. 321 (2009): 743-757.Website

"Congruences on monoids of order-preserving or order-reversing transformations on a finite chain." *Glasg. Math. J.*. 47 (2005): 413-424.Website

"The cardinal of various monoids of transformations that preserve a uniform partition." *Bulletin of the Malaysian Mathematical Sciences Society*. 35.4 (2012): 885-896.

"The cardinal and the idempotent number of various monoids of transformations on a finite chain." *Bulletin of the Malaysian Mathematical Sciences Society*. 34.2 (2011): 79-85. Abstract

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