1. Razygraev, N.P., Ermolov, I.N., and Shcherbinskii, V.G., A Method for Ultrasonic Testing of Material Quality, USSR Inventor?s Certificate no. 491 092, Byull. Izobret., 1975, no. 4.
2. Ermolov, I.N., Razygraev, N.P., and Shcherbinskii, V.G., The Use of Acoustic Head Waves for Ultrasonic Testing, Defektoskopiya, 1978, no. 1, pp. 33?38.
3. Ermolov, I.N., Razygraev, N.P., and Shcherbinskii, V.G., Study of the Process of Formation of Head Wave Acoustic Field in a Controlled Environment, Defektoskopiya, 1978, no. 11, pp. 5?10.
4. Ermolov, I.N., Razygraev, N.P., and Shcherbinskii, V.G., Study of Space Attenuation of Ultrasonic Head Waves, Defektoskopiya, 1979, no. 1, pp. 37?40.
5. Razygraev, N.P. and Shcherbinskii, V.G., Method of Ultrasonic Flaw Detection of Materials, USSR Inventor?s Certificate no. 502 211, Byull. Izobret., 1976, no. 5.