@article{TUW-120985, author = {Retscher, G{\"u}nther}, title = {Augmentation of Indoor Positioning Systems with a Barometric Pressure Sensor for Direct Altitude Determination in a Multi-storey Building}, journal = {Cartography and Geographic Information Science}, year = {2007}, volume = {34}, number = {4}, pages = {305--310}, url = {http://www.ingentaconnect.com/content/acsm/cagis/2007/00000034/00000004} }