1. Flowmeters;Hayward,1979
2. Effects of Pulsating Flow on an Ultrasonic Gas Flowmeter;Håkansson,1993
3. Installation Effect and Self-Diagnostics for Ultrasonic Flow Measurement;Carlander,2001
4. Ultrasonic Flow meters. Flow Measurement;Lynnworth,2001
5. J. Delsing, US patent 5 796 009, Method for meausing in a fluid with the aid of sing-around technique.