@article{PORMA_1962__21_4_114893,
     author = {Morgado, Jos\'e},
     title = {On the closure operators of the ordinal product of partially ordered sets},
     journal = {Portugaliae mathematica},
     pages = {209--220},
     publisher = {mathdoc},
     volume = {21},
     number = {4},
     year = {1962},
     mrnumber = {0148574},
     zbl = {0107.25301},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1962__21_4_114893/}
}