@article{GDZPPN002028891,
title = {Extremal tests for scalar functions of several real variables at degenerate critical points.},
journal = {Aequationes mathematicae},
volume = {13},
year = {1975},
pages = {89-96},
zbl = {0316.26008},
url = {http://dml.mathdoc.fr/item/GDZPPN002028891}
}
Cushing, J.M. Extremal tests for scalar functions of several real variables at degenerate critical points.. Aequationes mathematicae, Tome 13 (1975) pp. 89-96. http://gdmltest.u-ga.fr/item/GDZPPN002028891/