1. Thrust programming: in a central gravitational field;Lur'e,1965
2. Sur la résolution qualitative du problème restreint des trois corps;Jevi-Civita;Opere mathematiche,1956
3. Kustanheimo, P. and Stiefel: Perturbation theory of Kepler motion based on spinor regularization. Journal für die reine und angewandte Mathematik, 218/1965, 204-219
4. Methods of regularization for computing orbits in celestial mechanics;Stiefel;NSA contractor report,1967