1. On a class of hypoelliptic operators;Grushin;Math USSR-Sb.,1970
2. Some opial, Lyapunov, and de la Vallée Poussin inequalities with nonhomogeneous boundary conditions;Brown;J. Inequal. Appl.,2000
3. Applications of a one-dimensional Sobolev inequality to eigenvalue problems;Brown;J. Differential Integral Equations,1996
4. On an oscillation criterion of de la Vallée-Poussin;Cohn;Quart. J. Math. Oxford Ser. (2),1988
5. Rui A.C. Ferreira, Fractional De La Vallée Poussin inequalities, arXiv preprint arXiv:1805.09765.