1. Electronic sound absorber;Olson;Journal of the Acoustical Society of America,1953
2. Operational Amplifiers—Design and Application;Tobey,1971
3. Electronic sound absorber;Bleazey;Journal of the Audio Engineering Society,1962
4. Developments in active attenuators;Leventhall,1976
5. The active control of sound propagation in long ducts;Swinbanks;Journal of Sound and Vibration,1973