» Introduction to Bending Elements    Piezo Systems Corp.    http://www.piezo.com/bendedu.html

» Piezo Theory    Discusses the historic background, piezoelectric constants, soft versus hard ceramics, behavior of elements, resonance frequencies, applications, new materials and applications.    http://www.americanpiezo.com/piezo_theory/

» Recommended Reading about Piezoelectricity    PIEZO SYSTEMS, INC.    http://www.piezo.com/reading.html

» Smart Material, Corp. (Germany)    Advanced piezoelectric Materials and Components    http://www.smart-material.com

» Theory and Applications of Piezo Ceramic Actuators and PZT NanoPositioning Systems    Physikinstrumente (Germany) - very good information about piezo actuators and positioning systems.    http://www.physikinstrumente.com/tutorial/index.html