@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/