An interface circuit for R-C impedance sensors with a relaxation oscillator. - Stoyan N. Nihtianov; Georgi P. Shterev; Blagoy P. Iliev; Gerard C. M. Meijer (IEEE Trans. Instrum. Meas., 2001)

Impedance measurements with second-order harmonic oscillator for testing food sterility. - Stoyan N. Nihtianov; Georgi P. Shterev; Nikolay Petrov; Gerard C. M. Meijer (IEEE Trans. Instrum. Meas., 2001)