@article{JCA_2006_13_1_JCA_2006_13_1_a3,
     author = {S. Guti\'errez},
     title = {A {Necessary} {Condition} for the {Quasiconvexity} of {Polynomials} of {Degree} {Four}},
     journal = {Journal of convex analysis},
     pages = {51--6},
     publisher = {mathdoc},
     volume = {13},
     number = {1},
     year = {2006},
     url = {http://geodesic.mathdoc.fr/item/JCA_2006_13_1_JCA_2006_13_1_a3/}
}