@article{1183739769,
author = {Lachlan, A. H. and Lebeuf, R.},
title = {Countable Initial Segments of the Degrees of Unsolvability},
journal = {J. Symbolic Logic},
volume = {41},
number = {1},
year = {1976},
pages = { 289-300},
language = {en},
url = {http://dml.mathdoc.fr/item/1183739769}
}
Lachlan, A. H.; Lebeuf, R. Countable Initial Segments of the Degrees of Unsolvability. J. Symbolic Logic, Tome 41 (1976) no. 1, pp. 289-300. http://gdmltest.u-ga.fr/item/1183739769/