1. A sonar sensor for accurate 3D target localisation and classification;Akbarally,1995
2. Classification of indoor environment using only one ultrasonic sensor;Barat,2001
3. Neural network-based target differentiation using sonar for robotics applications;Barshan,2000
4. Using ultrasonic for the recognition of a real space;Corion,1996
5. Ultrasonics;Cracknell,1982