Abramov, Sergei A. (1989). Rational solutions of linear differential and difference equations with polynomial coefficients. USSR Computational Mathematics and Mathematical Physics. 29 (6): 7—12. doi:10.1016/s0041-5553(89)80002-3. ISSN0041-5553.
Abramov, Sergei A. (1989). Rational solutions of linear differential and difference equations with polynomial coefficients. USSR Computational Mathematics and Mathematical Physics. 29 (6): 7—12. doi:10.1016/s0041-5553(89)80002-3. ISSN0041-5553.