A Rationality Result for Kovacic's Algorithm. - Marius van der Put; Peter A. Hendriks (ISSAC, 1993)

Galois Action on Solutions of a Differential Equation. - Peter A. Hendriks; Marius van der Put (J. Symb. Comput., 1995)

An Algorithm Determining the Difference Galois Group of Second Order Linear Difference Equations. - Peter A. Hendriks (J. Symb. Comput., 1998)