@article{1183732766,
author = {Feferman, Solomon},
title = {Degrees of Unsolvability Associated with Classes of Formalized Theories},
journal = {J. Symbolic Logic},
volume = {22},
number = {1},
year = {1957},
pages = { 161-175},
language = {en},
url = {http://dml.mathdoc.fr/item/1183732766}
}
Feferman, Solomon. Degrees of Unsolvability Associated with Classes of Formalized Theories. J. Symbolic Logic, Tome 22 (1957) no. 1, pp. 161-175. http://gdmltest.u-ga.fr/item/1183732766/