1. Caviness, B.F. & Rothstein, M., A Liouville Theorem on Integration in Finite Terms for Line Integrals. Comm. Algebra 3(1975) pp. 781–795.
2. Davenport,J.H. & Trager,B.M., On the Parallel Risch Algorithm (II). To appear.
3. ffitch,J.P., User-based Integration Software. Proc. SYMSAC 81, pp. 245–248
4. Kaplansky, I., An Introduction to Differential Algebra. Publications de l'Institut de Mathėmatique de l'Universitė de Nancago V, Hermann, Paris, 1957 (2nd. ed. 1976).
5. Kolchin, E.R., Differential Algebra and Algebraic Groups. Academic Press, London, 1973.