1. Münchschwander P, Heinisch R, Kracke R, Lehmann E, Rahn T, Stuchly H. Feste Fahrbahn. Edition ETR, Darmstadt, Germany, 1997.
2. Henschen J, Colla C, Karst G, Krause M, Kretzschmar F, Maierhofer C, Mielentz F, Milman B, Schneider G, Wöstmann J, Wiggenhauser H. Zerstörungsfreie Messungen zur Beurteilung des inneren Zustandes Fester Fahrbahnen der Deutschen Bahn AG, Anhang 1 (Non-destructive measurements for the evaluation of the inner condition of Deutschen Bahn's slab–tracks. Appendix 1). Internal report: BAM (VII-P10-01) 0211-VII-0323/7305/17, Berlin, 1999.
3. Ultrasonic pulse echo technique for concrete elements using synthetic aperture;Krause,1997
4. Ultrasonic imaging of concrete members using an array system;Krause,2000
5. Impact-echo, nondestructive evaluation of concrete and masonry;Sansalone,1997