“…For simplicity, the further statement of change space L 2,1 (Γ T ), replacing this space on CL 2,1 (Γ T ) ⊂ L 2,1 (Γ T ) (CL 2,1 (Γ T ) is the space of functions from L 2,1 (Γ T ), that are continuous on t in the norm L 2 (Γ)), when this f (x, t) ∈ CL 2,1 (Γ T ) (the latter is easy condition in applications). In this case, as shown in the work [12], the weak solution y(x, t) ∈ V 1,0 (a, Γ T ) of problem (5), (6) for any 0 < T < ∞ representable in the form of the series…”