@article{SF_1972__5_133927,
     author = {G. Markowsky},
     title = {Idempotents and product representations with applications to the semigroup of binary relations.},
     journal = {Semigroup forum},
     pages = {95--119},
     publisher = {mathdoc},
     volume = {5},
     year = {1972},
     zbl = {0264.20047},
     url = {http://geodesic.mathdoc.fr/item/SF_1972__5_133927/}
}