@article{AULFM_1997_09_a1,
     author = {Wro\'nski, Stanis{\l}aw},
     title = {On proper subuniverses of a boolean algebra},
     journal = {Acta Universitatis Lodziensis. Folia Mathematica},
     publisher = {mathdoc},
     volume = {09},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AULFM_1997_09_a1/}
}