2) 岡田清・六車煕: コンクリートハンドブック, 朝倉書店, pp. 499-555, 1985. 6.
3) Bradfield, G. and Woodroffe, E. P. H.: Determining the Thickness of Concrete Pavement by Mechanical Waves, Direct-beam Method, Mag. of Concrete Research, pp. 16-46, 1964.
4) Chung, H. W. and Laur, K. S.: Diagnosing in situ Concrete by Ultrasonic Pulse Technique, Concrete International, pp. 42-49, Oct. 1983.
5) Knab, L. T., Blessing, G. V. and Clifton, J. R.: Laboratory Evaluation of Ultrasonics for Crack Detection in Concrete, ACI Journal, pp. 17-27, Jan./Feb. 1983.