"Elliptische differentiaalvergelijkingen." . . "Pseudodifferentialoperator." . . "Differentialoperator." . . . . "Operatori pseudodifferenziali." . . "Elliptischer Differentialoperator." . . "Contorno (Matemáticas)" . . "Problemi al contorno." . . "Randwaardeproblemen." . . "Elliptische Differentialgleichung." . . "Problemas de fronteras libres (Matemáticas)" . . "Ecuaciones diferenciales elípticas." . . "Probleme la limită." . . "Equazioni differenziali ellittiche." . . "Indextheorie." . . "Elliptischer Operator." . . "Operatori pseudo-diferentiali." . . "Teoriâ indeksa elliptičeskih kraevyh zadač" . . . . . . . "Index theory of elliptic boundary problems"@en . "Index theory of elliptic boundary problems" . . . . . . "Teorija indeksa ėlliptičeskich kraevych zadač" . . . . . . . . . . . . . . "Index theory of elliptic Boundary problems" . . . . . . . . . . . . . . . . . . . . . . . . . "Randwertproblem." . . "Elliptisches Randwertproblem." . .