@article{SF_1970__1_133777,
     author = {B.M. Schein},
     title = {Relation algebras and function semigroups.},
     journal = {Semigroup forum},
     pages = {1--62},
     year = {1970},
     volume = {1},
     zbl = {0197.29404},
     url = {http://geodesic.mathdoc.fr/item/SF_1970__1_133777/}
}