1. R. Bittner,Rachunek operatorów w przestrzeniach liniowych (Warszawa, 1974) (in Polish).
2. R. Bittner, Algebraic and analytic proporties of solutions of abstract differential equations,Rozprawy Matematyczne,41 (1964), 1–63.
3. R. Bittner, E. Mieloszyk, About eigenvalues of differential equations in the operational calculus,Zeszyty Naukowe PG, Matematyka,XI (1978), 87–99.
4. R. Bittner, E. Mieloszyk, Application of the operational calculus to solving non-homogeneous linear partial differential equations of the first order with real coefficients,Zeszyty Naukowe PG, Matematika,XII (1982), 33–45.
5. R. Bittner, E. Mieloszyk, Properties of eigenvalues and eigenelements of some difference equations in a given operational calculus,Zeszyty Naukowe UG. Matematyka,5 (1982), 5–18.