@article{PORMA_1959__18_3_114822,
     author = {Cunkle, C.H.},
     title = {A note on {Boolean} operations},
     journal = {Portugaliae mathematica},
     pages = {177--179},
     year = {1959},
     volume = {18},
     number = {3},
     mrnumber = {0124248},
     zbl = {0111.02402},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1959__18_3_114822/}
}