@article{CLTM_1995_1995_1_a4,
     author = {Preston, G. B.},
     title = {Productos de semigrupos inversos.},
     journal = {Collectanea mathematica},
     pages = {151-157},
     year = {1995},
     volume = {46},
     number = {1-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CLTM_1995_1995_1_a4/}
}