@article{1183736503,
author = {Boolos, George and Putnam, Hilary},
title = {Degrees of Unsolvability of Constructible Sets of Integers},
journal = {J. Symbolic Logic},
volume = {33},
number = {1},
year = {1968},
pages = { 497-513},
language = {en},
url = {http://dml.mathdoc.fr/item/1183736503}
}
Boolos, George; Putnam, Hilary. Degrees of Unsolvability of Constructible Sets of Integers. J. Symbolic Logic, Tome 33 (1968) no. 1, pp. 497-513. http://gdmltest.u-ga.fr/item/1183736503/