1. An automatic low-frequency analyzer;Barbour;Rev. Sci. Inst.,1947
2. The measurement of power spectra;Blackman,1959
3. Heterodyne spectral noise analyzer;Burik;Rev. Sci. Inst.,1963
4. A general purpose phase-sensitive detector;Faulkner;Electronic Eng.,1964
5. Spectral analyzer for EEG;Goldstein;Electroenceph. clin. Neurophysiol.,1961