@article{GDZPPN00218124X,
title = {Perturbation theory of Kepler motion based on spinor regularization.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {218},
year = {1965},
pages = {204-219},
zbl = {0151.34901},
url = {http://dml.mathdoc.fr/item/GDZPPN00218124X}
}
Stiefel, E.; Kustaanheimo, P. Perturbation theory of Kepler motion based on spinor regularization.. Journal für die reine und angewandte Mathematik, Tome 218 (1965) pp. 204-219. http://gdmltest.u-ga.fr/item/GDZPPN00218124X/