@article{10_4064_fm_41_1_21_28,
     author = {H. Rasiowa and Roman Sikorski},
     title = {On existential theorems in non-classical functional calculi},
     journal = {Fundamenta Mathematicae},
     pages = {21--28},
     publisher = {mathdoc},
     volume = {41},
     number = {1},
     year = {1955},
     doi = {10.4064/fm-41-1-21-28},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-41-1-21-28/}
}