Barbagli, F., Salisbury, K., & Prattichizzo, D. (2005). Multi-point Interaction with Real and Virtual Objects. Springer-Verlag GmbH..

Barbagli, Federico, Kenneth Salisbury, and Domenico Prattichizzo. Multi-point Interaction with Real and Virtual Objects. Berlin Heidelberg: Springer-Verlag GmbH., 2005.

Barbagli, Federico, et al. Multi-point Interaction with Real and Virtual Objects. Springer-Verlag GmbH., 2005.