TY  - RPRT
TI  - Preliminary Goddard geopotential using optical tracking data and a comparison with SAO models
AU  - Lerch, F. J.
AU  - Wagner, C. A.
AU  - Putney, B. H.
AU  - Nickerson, K. G.
PY  - 1971
UR  - https://ntrs.nasa.gov/citations/19720005238
ID  - 19720005238
ER  -