We are preparing a full text appendix based upon the following papers:

Everhart, E. and Pitkin, E. T. (1983). Universal variables in the two-body problem, Am. J. Phys. 51/8 712-717.

abstract in ADS

Goodyear, W.H. (1965). Completely general closed-form solution for coordinates and partial derivatives of the two-bosy problem, AJ 70, 189-192. See also the errata corrige published on page 446 of the same volume.

It may also contain some additional results.

Andrea Milani 2010-04-18