@article{10_21136_CMJ_1970_100989,
     author = {Schwarz, \v{S}tefan},
     title = {On the semigroup of binary relations on a finite set},
     journal = {Czechoslovak Mathematical Journal},
     pages = {632--679},
     publisher = {mathdoc},
     volume = {20},
     number = {4},
     year = {1970},
     doi = {10.21136/CMJ.1970.100989},
     mrnumber = {0296190},
     zbl = {0228.20034},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1970.100989/}
}