Puspita, N.P., Wijayanti, I.E. and Surodjo, B. 2022. The Necessary and Sufficient Condition of Clean R-Coalgebra e⇀C↼e. Journal of the Indonesian Mathematical Society. 28, 2 (Jul. 2022), 215–220. DOI:https://doi.org/10.22342/jims.28.2.1066.215-220.