Benedetto Intrigila, Ivano Salvo, and Stefano Sorgi. "A characterization of weakly Church-Rosser abstract reduction systems that are not Church-Rosser." _Information and Computation_ 171, no. 2 (2001): 137–155. Academic Press, Inc.. ISSN: 0890-5401. DOI: 10.1006/inco.2001.2945.