NavApp: An indoor navigation application: A smartphone application for libraries - Iman Abu Hashish; Gianmario Motta; Michela Meazza; Guoqing Bu; Kaixu Liu; Lorenzo Duico; Antonella Longo (14th Workshop on Positioning, Navigation and Communications, WPNC 2017, Bremen, Germany, October 25-26, 2017, 2017)