1. H. Galster, pH Measurement: Fundamentals, Methods, Applications, Instrumentation, VCH, New York, 1991.
2. Fiber optic pH probe for physiological use
3. Recent progress in fiber optic pH sensing
4. Leiner, M.J.P., O.S. Wolfbeis, in: O.S. Wolfbeis (Ed.), Fiber Optical Chemical Sensors and Biosensors, Vol I, CRC Press, Boca Raton, FL, 1991, p.359.
5. Optical sensor for high pH values