@article{GDZPPN002302055,
title = {A Short Proof of Schaefer's Theorem.},
journal = {Mathematische Annalen},
volume = {189},
year = {1970},
pages = {155-156},
zbl = {0176.10502},
url = {http://dml.mathdoc.fr/item/GDZPPN002302055}
}
WONG, Y.Ch. A Short Proof of Schaefer's Theorem.. Mathematische Annalen, Tome 189 (1970) pp. 155-156. http://gdmltest.u-ga.fr/item/GDZPPN002302055/