Manachai Toahchoodee Indrakshi Ray Kyriakos Anastasakis Geri Georg Behzad Bordbar Ensuring spatio-temporal access control for real-world applications. 13-22 2009 SACMAT http://doi.acm.org/10.1145/1542207.1542212 conf/sacmat/2009 db/conf/sacmat/sacmat2009.html#ToahchoodeeRAGB09