@Misc{ MaiMugVec22, author = { Maione, Alberto and Mugnai, Dimitri and Vecchi, Eugenio }, title = { Variational methods for nonpositive mixed local-nonlocal operators }, journal = { }, year = { 2022 }, pages = { }, URL = { http://cvgmt.sns.it/paper/5673/ }, note = { cvgmt preprint} }