1. Über Schalluntersuchungen an Achsen von Schienenfahrzeugen;Martin,1952
2. Hopes and needs for the future of railway industry NDT;Clark;Insight,1995
3. Experimental system for ultrasonic testing of axle sets of diesel-engine trains;Grum;Insight,2000
4. Recent advantage in ultrasonic inspection of railway axles and wheels;Wüstenberg;Insight,2001
5. Non-destructive testing of axles fitted to railway wheel sets;Hall;Insight,1995