1. K. Iwamoto and I. Kamata, Liquid-level sensor with optical fibers, Appl. Opt., 31 (1992) 51–54.
2. A.T. Akhmadiev, E.N. Belotserkovskii and A.L. Patlakh, Current state-of-the-art and future prospects for the development of fiber optic level transducers, Sov. J. Opt. Technol., 53 (1986) 363–369.
3. K. Spenner, M.D. Singh, H. Schult and H.J. Boehnel, Experimental investigation of fiber optic liquid level sensors and refractometers, Proc. 1st Int. Conf. Optical Fiber Sensors, London, UK, 1983, pp. 96–99.
4. K. Spenner, Faseroptische füllstand sensoren für flüssigkeiten, Tech. Messen, 51 (1984) 329–332.
5. J. Niewisch, Design and applications of fiber-optic liquid-level sensor, Siemens Forsch. Entwicklber., 15 (1986) 115–119.