The Explicit Computation of Integration Algorithms and First Integrals for Ordinary Differential Equations with Polynomial Coefficients Using Trees.

P. E. Crouch Robert L. Grossman The Explicit Computation of Integration Algorithms and First Integrals for Ordinary Differential Equations with Polynomial Coefficients Using Trees. 89-94 1992 ISSAC http://doi.acm.org/10.1145/143242.143277 db/conf/issac/issac92.html#CrouchG92