REDUCE-Procedures for the Study of Adjoint Symmetries of Second-Order Differential Equations. - W. Sarlet; J. Vanden Bonne (J. Symb. Comput., 1992)

Complex Second-Order Differential Equations and Separability. - W. Sarlet; G. Thompson (Appl. Algebra Eng. Commun. Comput., 2001)