1. Nondestructive Testing Handbook;ASNT,1959
2. Recommended Practice SNT-TC-1A;ASNT,1988
3. Nondestructive Testing Handbook;ASNT,1991
4. C-1259–94;ASTM,1994
5. Tabuluation of some integral functions describing diffraction effects in the ultrasonic field of a circular source;Benson;J. Acoust. Soc. Amer.,1974