@ARTICLE {18930,
author={R. Queirós and F. Alegria and P.M. Girão and A. Serra},
doi={10.1016/j.ultras.2015.06.018},
journal={IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control},
title={A multi-frequency method for ultrasonic ranging},
year={2015},
month={December},
volume={63},
number={1},
pages={86-93},
ISSN={0885-3010}
}