Modern Sensors Handbook
Modern Sensors Handbook, edited by Pavel Pipka and Alois Tipek, is a PDF book that covers all aspects of modern sensor technology. Chapter 7 focuses on level, position and distance sensing. It covers, among other things, capacitive, ultrasonic, radar and hydrostatic level sensors. The chapter also has a list of both print and online references for further study. Go to http://tinyurl.com/yzegew9 for a direct link.