1. Solar Energy for Future Heat Pumps;Penrod,1960
2. Solar Energy Heat Source for Tomorrow's Heat Pump;Penrod;Heating, Piping and Air Conditioning,1960
3. Air Conditioning with the Heat Pump;Penrod;Kentucky Engineering,1956
4. Integrated Ground Coil and Solar Collector for Heat Pumps;Prasanna,1956
5. Solar Energy Measurements (1951–1960) at University of Kentucky;Penrod;University of Kentucky Engineering Experiment Station Bulletin,1961