1. Sea Surface Topography From Space, vol. 1 and 2;Apel,1972
2. Oceanography and the marine geoid;Apel,1974
3. A synopsis of Seasat-A scientific contributions;Apel;Seasat-A Scientific Contributions,1974
4. Observations of oceanic internal and surface waves from the Earth Resources Technology satellite;Apel;J. Geophys. Res.,1975
5. The scanning multichannel microwave radiometer;Barath,1975