1. Parker, W.R., Sills, G.C. and Paske, R.E.A. “In situ Nuclear Density Measurements in Dredging Practice and Control”, Symposium on Dredging Technology, 17–19 Sept. 1975, published by BHRA Fluid Engineering, Cranfield, Bedford, England.
2. Bakker, D.J. “Density Measurements in conjunction with Echo-Sounding”, The Hydrographic Journal, no. 14, pp. 21–27, April 1979.
3. Kirby, R. and Parker, W.R. “Seabed Density Measurements related to Echo-Sounder Records”, The Dock and Harbour Authority, pp. 423–424, March 1974. Schmidt, D.Ph. and Janssen H.C. “Acoustic Silt-Density Measurements, a Feasibility Study”, Institute of Applied Physics Tech.rep.no. 910–281, July 1980 (in Dutch).
4. Schmidt, D.Ph., Janssen, H.C. and Berkhout, A.J.B. “Prediction of Sediment Density Profiles by means of Echo-Sounding”, ULTRASONICS INTERNATIONAL 81, pp. 165–170, published by IPC Science and Technology Press Limited, Guildford,Surrey, England, 1981.
5. Westervelt, P.J. “Scattering of Sound by Sound”, J.Acoust.Soc. Am., Vol. 29, pp. 199–203, Febr. 1957.