1. The numerical determination of nominal libration point trajectories and development of a station-keeping strategy;Pernicka,1990
2. Study refinement of semi-analytical halo orbit theory;Gómez;ESA Contract No. 8625/89/D/MD(SC), Final Report,1991
3. Transfers between libration-point orbits in the elliptic restricted problem;Hiday,1992
4. Impulsive time-free transfers between halo orbits;Hiday,1992