TY  - RPRT
TI  - Optimal trajectories between Earth and Mars in their true planetary orbits.
AU  - Gravier, J. P.
AU  - Marchal, C.
AU  - Culp, R. D.
PY  - 1972
UR  - https://ntrs.nasa.gov/citations/19720036158
ID  - 19720036158
ER  -