W. Liao, B. Rosenhahn, and Y. Michael. International Society for Photogrammetry and Remote Sensing ISA workshop, La Grande Motte, France, (September 2015)
Y. Song, L. Zhang, and C. Giles. CIKM '08: Proceeding of the 17th ACM conference on Information and knowledge management, page 93--102. New York, NY, USA, ACM, (2008)