1. Computational methods for studying acoustic propagation in non-uniform waveguides;Beckemeyer;American Institute of Aeronautics and Astronautics Paper 73-1006,1973
2. A method of weighted residuals for the investigation of sound transmission in non-uniform ducts without flow;Eversman;Journal of Sound and Vibration,1975
3. A multi-modal solution for the transmission of sound in non-uniform ducts;Eversman;American Institute of Aeronatics and Astronautics Paper 76-497,1976
4. A wave envelope technique for wave propagation in non-uniform ducts;Kaiser,1976
5. Finite difference theory for sound propagation in a lined duct with uniform flow using the wave envelope technique;Baumeister;NASA Technical Paper 1001,1977