Ferroelectrics Newsletter:
Introduction to Bending Elements: Piezo Systems Corp.
NPL: Sensors & Functional Materials Group - Publications about piezoelectric materials: the UK's national standards laboratory, who look after the basic units of measurement such as time, mass and length which ensure consistency and traceability of measurements.
Piezo Theory: Discusses the historic background, piezoelectric constants, soft versus hard ceramics, behavior of elements, resonance frequencies, applications, new materials and applications.
Recommended Reading about Piezoelectricity: PIEZO SYSTEMS, INC.
Smart Material, Corp. (Germany): Advanced piezoelectric Materials and Components
Theory and Applications of Piezo Ceramic Actuators and PZT NanoPositioning Systems: Physikinstrumente (Germany) - very good information about piezo actuators and positioning systems.