Voir la notice de l'article provenant de la source Electronic Library of Mathematics
@article{DOCMA_2012__S3__a3, author = {Schm\"udgen, Konrad}, title = {Around {Hilbert's} 17th problem}, journal = {Documenta mathematica}, pages = {433--438}, publisher = {mathdoc}, volume = {Optimization Stories}, year = {2012}, language = {en}, url = {http://geodesic.mathdoc.fr/item/DOCMA_2012__S3__a3/} }
Schmüdgen, Konrad. Around Hilbert's 17th problem. Documenta mathematica, Optimization Stories (2012), pp. 433-438. http://geodesic.mathdoc.fr/item/DOCMA_2012__S3__a3/