1. GOST 17624-78. Ultrasonic Method of Determining Strength [in Russian].
2. S. K. Barashkov, V. Yu. Lyubinskoi, and A. V. Bobrov, ?Electrodynamic radiator in acousic apparatus for nondestructive control of the quality of concrete,? Beton Zhelezobeton, No. 5 (1986).
3. S. Ya. Edel'man, On-Site Investigations of the Bratsk Concrete Dam [in Russian], Énergiya Moscow (1975).
4. I. E. Pukhov, ?Investigations of the elastic characteristics of concrete directly in the mass of hydraulic structures,? Gidrotekh. Stroit., No. 8 (1977).