@article{MASLO_1980_30_2_a11,
     author = {Dvure\v{c}enskij, Anatolij},
     title = {On a sum of observables in a logic},
     journal = {Mathematica slovaca},
     pages = {187--196},
     year = {1980},
     volume = {30},
     number = {2},
     mrnumber = {587245},
     zbl = {0435.03040},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1980_30_2_a11/}
}