On a non-local problem for parabolic-hyperbolic equation with three   lines of type changing
  In the present work we investigate a boundary problem with non-local conditions, connecting values of seeking function on various characteristics for parabolic-hyperbolic equation with three lines of type changing. The considered problem is equivalently reduced to the system of Volterra integral equations of the second kind. 
Erkinjon Karimov, Sotvoldiev A.I
math.AP