@article{SF_1982__25_134589,
     author = {R.J. Koch and J.A. Hildebrant},
     title = {A note on idempotents.},
     journal = {Semigroup forum},
     pages = {386--386},
     publisher = {mathdoc},
     volume = {25},
     year = {1982},
     zbl = {0508.22007},
     url = {http://geodesic.mathdoc.fr/item/SF_1982__25_134589/}
}