@article{10_1017_S0017089500004468,
     author = {Kim, Ki Hang and Roush, Fred William},
     title = {The algebraic structure of the semigroup of binary relations on a finite set},
     journal = {Glasgow mathematical journal},
     pages = {57--68},
     year = {1981},
     volume = {22},
     number = {1},
     doi = {10.1017/S0017089500004468},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500004468/}
}