Periodic conjugation problem for linear elliptic equations of second order with constant coefficients (Q1646269)

The author solves a periodic boundary-value conjugation problem on the real axis for the elliptic differential operator \[ L:= \sum\limits_{k=0}^{2}a_{k}\frac{\partial^{2}}{\partial x^{2-k}\partial y^{k}} \] with constant coefficients on the complex plane.