Boundary-value problems for a fourth-order system of differential equations
Existence and uniqueness theorems for boundary value problems of the system \[ M^*MU(x,y,z)+C(x,y,z)U=F(x,y,z), \] where \(MU(x,y,z)=xU_{xx}-U_{yy}+U_{zz}\), C a positive definite matrix, U,F vector-functions, are proved.
scientific article; zbMATH DE number 4150912