@article{TRSPY_1972_121_a5,
     author = {V. P. Orevkov},
     title = {Undecidable classes of formulas for the constructive predicate {calculus.~I}},
     journal = {Informatics and Automation},
     pages = {100--108},
     publisher = {mathdoc},
     volume = {121},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1972_121_a5/}
}