@inproceedingsRautenberg_Henning_2007, title=New approach for the reliable measurement of acoustic impedance of liquids in an acoustic waveguide, volume=II, author=Rautenberg, Jens and Henning, Bernd, year=2007, pages=87–92 

@inproceedingsVössing_Rautenberg_Kehl_Henning_2007, title=Simultaneous transmitting and receiving with ultrasonic sensors, author=Vössing, Torsten and Rautenberg, Jens and Kehl, Romina and Henning, Bernd, year=2007