“…We quote papers [3,34], where for some δ ∈ (0, 1) and appropriate Banach spaces X, estimates like t −δ u X were obtained in the case of initial-boundary problems to autonomous linear subdiffusion equations. As for solvability of corresponding problems to equations like (1) in smooth classes: C δ ([0, T ], X), C k+α, k+α 2 ν (Ω T ), we refer to [10,13,16,22,27,23,24,31,40].…”