@article{SF_1987__36_134888,
     author = {J. Leech},
     title = {Constructing inverse monoids from small categories.},
     journal = {Semigroup forum},
     pages = {89--116},
     year = {1987},
     volume = {36},
     zbl = {0634.18002},
     url = {http://geodesic.mathdoc.fr/item/SF_1987__36_134888/}
}