@article{10_4064_fm_43_2_166_177,
     author = {Andrzej Grzegorczyk},
     title = {Some proofs of undecidability of arithmetic},
     journal = {Fundamenta Mathematicae},
     pages = {166--177},
     publisher = {mathdoc},
     volume = {43},
     number = {2},
     year = {1956},
     doi = {10.4064/fm-43-2-166-177},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-43-2-166-177/}
}