M. Becker, J. Mueller, A. Hotho, und G. Stumme. Conference on Pervasive and Ubiquitous Computing Adjunct Publication, Seite 1175--1182. New York, NY, USA, (2013)
S. Brakatsoulas, D. Pfoser, R. Salas, und C. Wenk. Proceedings of the 31st International Conference on Very Large Data Bases, Seite 853--864. VLDB Endowment, (2005)