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3. R. Bittner,Rachunek operatorów w przestrzeniach liniowych (Warszawa, 1974).
4. R. Bittner and E. Mieloszyk, Properties of eigenvalues and eigenelements of some difference equations in a given operational calculus,Zesz. Nauk. UG Gdańsk, Matematyka,5 (1981), 5–18.
5. R. Bittner and E. Mieloszyk, Application of the operational calculus to solving non-homogeneous linear partial differential equations of the first order with real coefficients,Zesz. Nauk. PG Gdańsk, Matematyka,12 (1982), 33–45.