Kosuke Watanabe Nobuo Kawaguchi A Smartphone Short-Range Path Estimation with Hyperbolic Function for Spinning Magnet Marker. 459-460 2019 PerCom Workshops https://doi.org/10.1109/PERCOMW.2019.8730728 conf/percom/2019w db/conf/percom/percomw2019.html#WatanabeK19