@article{1183738953,
author = {Jockusch, Carl G.},
title = {$\Pi^0\_1$ Classes and Boolean Combinations of Recursively Enumerable Sets},
journal = {J. Symbolic Logic},
volume = {39},
number = {1},
year = {1974},
pages = { 95-96},
language = {en},
url = {http://dml.mathdoc.fr/item/1183738953}
}
Jockusch, Carl G. $\Pi^0_1$ Classes and Boolean Combinations of Recursively Enumerable Sets. J. Symbolic Logic, Tome 39 (1974) no. 1, pp. 95-96. http://gdmltest.u-ga.fr/item/1183738953/