@article{1183740114,
author = {Simpson, Stephen G.},
title = {Sets Which Do Not Have Subsets of Every Higher Degree},
journal = {J. Symbolic Logic},
volume = {43},
number = {1},
year = {1978},
pages = { 135-138},
language = {en},
url = {http://dml.mathdoc.fr/item/1183740114}
}
Simpson, Stephen G. Sets Which Do Not Have Subsets of Every Higher Degree. J. Symbolic Logic, Tome 43 (1978) no. 1, pp. 135-138. http://gdmltest.u-ga.fr/item/1183740114/