1. A modified segmentation approach for analyzing plane wave propagation in non-uniform ducts with mean flow
2. Nayfeh, A. H., Kaiser, J. E. & Shaker, B. S., 1979, A wave envelop analysis of sound propagation in non-uniform circular ducts with compressible mean flows. NASA contractor 3109 Report
3. Nayfeh, A. H. Shaker, B. S. & Kaiser, J. E. 1980, Transmission of sound through nonuniform circular ducts with compressible mean flows AIAA Journal, Vol.18, pp515-525.