Steven Verstockt Viktor Slavkovikj Pieterjan De Potter Jürgen Slowack Rik Van de Walle Multi-modal Bike Sensing for Automatic Geo-annotation - Geo-annotation of Road/Terrain Type by Participatory Bike-sensing. 39-49 2013 SIGMAP conf/sigmap/2013 db/conf/sigmap/sigmap2013.html#VerstocktSPSW13 https://ieeexplore.ieee.org/document/7184668/