Tactile tissue characterisation by piezoelectric systems
R. Stroop, D.O. Uribe, M.O. Martinez, M. Brökelmann, T. Hemsel, J. Wallaschek, Journal of Electroceramics 20 (2008) 237–241.

Development of a biomedical tissue differentiation system using piezoelectric actuators
D.O. Uribe, R. Stroop, T. Hemsel, J. Wallaschek, in: Frequency Control Symposium, 2008 IEEE International, 2008, pp. 91–94.

Blind Acoustic Beamforming Based on Generalized Eigenvalue Decomposition
E. Warsitz, R. Haeb-Umbach, IEEE Transactions on Audio, Speech, and Language Processing 15 (2007) 1529–1539.