@article{DAN_1987_294_4_a2,
     author = {V. P. Orevkov},
     title = {Lower bounds for the lengths of deductions in arithmetic in terms},
     journal = {Doklady Akademii Nauk},
     pages = {784--787},
     publisher = {mathdoc},
     volume = {294},
     number = {4},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_294_4_a2/}
}