@article{10_4064_cm_20_2_209_214,
     author = {J. P{\l}onka},
     title = {On sums of direct systems of {Boolean} algebras},
     journal = {Colloquium Mathematicum},
     pages = {209--214},
     publisher = {mathdoc},
     volume = {20},
     number = {2},
     year = {1969},
     doi = {10.4064/cm-20-2-209-214},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-20-2-209-214/}
}