A characterization of all classes of idempotent groupoids having no more than two essentially binary term operations with respect to small finite models is given.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-1-5, author = {J. Ga\l uszka}, title = {Two-generated idempotent groupoids with small clones}, journal = {Colloquium Mathematicae}, volume = {89}, year = {2001}, pages = {59-68}, zbl = {0998.08002}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-1-5} }
J. Gałuszka. Two-generated idempotent groupoids with small clones. Colloquium Mathematicae, Tome 89 (2001) pp. 59-68. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm90-1-5/