G. K. Ho, K. Sundaresan, S. Pourkamali, and F. Ayazi, “Micromechanical IBARS: tunable high-Q resonators for temperature-compensated reference oscillators,” Journal of Micro-Electro-Mechanical-Systems, vol. 19, no. 3, pp. 503–515, June 2010. 
G. K. Ho, K. Sundaresan, S. Pourkamali, and F. Ayazi, “Micromechanical IBARS: tunable high-Q resonators for temperature-compensated reference oscillators,” Journal of Micro-Electro-Mechanical-Systems, vol. 19, no. 3, pp. 503–515, June 2010.