1. Skogen, N. 1951 Kgl. Norske Vidensk. Selskab Forh. 24,68–71.
2. Wang, C.-Y. 1968 J. Fluid Mech. 32,55–68.
3. Raney, W. P. , Corelli, J. C. & Westervelt, J. P. 1954 J. Acoust. Soc. Am. 26,1006–1014.
4. Skavlem, S. & Tjøtta, S. 1955 J. Acoust. Soc. Am. 27,26–33.
5. Bertelsen, A. 1971 Thesis (in Norwegian),Department of Physics, University of Bergen, Norway.