@article{SF_1991__43_3_135096,
     author = {M. Breen},
     title = {A maximal chain of principal ideals in the semigroup of binary relations on a finite set.},
     journal = {Semigroup forum},
     pages = {63--76},
     year = {1991},
     volume = {43},
     number = {3},
     zbl = {0727.20040},
     url = {http://geodesic.mathdoc.fr/item/SF_1991__43_3_135096/}
}