1. Walt Kester (2004), Analog-Digital Conversion, Analog Devices, 2004, ISBN 0-916550-27-3, Chapter 3.
2. The Data Conversion Handbook, Elsevier/Newnes (2005), ISBN 0-7506-7841-0, Chapter 3.
3. John L. Lindesmith, “Voltage-to-Digital Measuring Circuit,” U.S. Patent 2,835,868, filed September 16, 1952, issued May 20, 1958.
4. Paul Klonowski, “Analog-to-Digital Conversion Using Voltage-to-Frequency Converters,” Application Note AN-276, Analog Devices, Inc.
5. James M. Bryant, “Voltage-to-Frequency Converters,” Application Note AN-361, Analog Devices, Inc.