1. Fiber-optic fluid level sensor;Belkerdid,1985
2. Fiber-optic methods of level sensing;Rakucewicz;IEEE Sensors J.,1986
3. A digital fiber-optic liquid level sensor;Morris;J. Lightwave Technol.,1987
4. L. A. Danisch, “Fiber optic liquid level sensor,” US Patent No. 4880971, 1989.
5. S.H. Woodside, “Fiber optic continuous liquid level sensor”, US Patent No. 4994682, 1991.