1. Baumgarte, J.: Numerical Stabilization of the Differential Equations of Keplerian Motion, Celes. Mech. 5, 490–501, (1972).
2. Baumgarte, J.: Stabilization by Modification of the Lagrangian, Celes. Mech. 13, 247–251, (1976).
3. Baumgarte, J.: Stabilization, Manipulation and Analytic Step Adaption, Long-Time Predictions in Dynamics, edited by V. Szebehely and B. D. Tapley, Nato Advanced Study Institutes Series, Series C-Mathematical and Physical Sciences, Vol. 26, D. Reidel Publishing Company, Dordrecht-Holland/Boston-U.S.A., (1976).
4. Stiefel, E.L. and Scheifele, G.: Linear and Regular Celestial mechanics, Springer, Berlin-Heidelberg-New York, (1971).