1. R. A. Adams, Sobolev Spaces. Academic Press, New York, 1975.
2. A. Ambrosetti, M. Badiale, S. Cingolani, “Semiclassical states of nonlinear Schrödinger equations with bounded potentials”, Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. Rend. Lincei (9) Mat. Appl. 7 (1996), no. 3, 155–160.
3. W.H. Aschbacher, J. Fröhlich, G.M. Graf, K. Schnee, and M. Troyer, “Symmetry breaking regime in the nonlinear hartree equation”, J. Math. Phys. 43, 3879–3891 (2002).
4. D. Bambusi, S. Cuccagna, “On dispersion of small energy solutions to the nonlinear Klein Gordon equation with a potential”, Amer. J. Math. 133 (2011), no. 5, 1421–1468.
5. V. Benci, D. Fortunato, Variational methods in nonlinear field equations. Solitary waves, hylomorphic solitons and vortices. Springer Monographs in Mathematics. Springer Cham Heidelberg New York Dordrecht London, 2014.