Zubairu, Muhammad Mansur. 2023. “On the Subsemigroup Generated by Idempotents of the Semigroup of Order Preserving and Decreasing Contraction Mappings of a Finite Chain: On the Subsemigroup Generated by Idempotents”. Journal of the Nigerian Mathematical Society 42 (2):140-52. https://ojs.ictp.it/jnms/index.php/jnms/article/view/934.