Singmin, Andrew: Beginning Digital Electronics Through Projects, s. 9. Newnes, 2001. ”Signals come from transducers...” ISBN 0-7506-7269-2Teoksen verkkoversio.
Miller, Mark R.: Electronics the Easy Way, s. 232–239. Barron's Educational Series, 2002. ”Until the radio came along...” ISBN 0-7641-1981-8Teoksen verkkoversio.
Chen, Wai-Kai: The electrical engineering handbook, s. 101. Academic Press, 2005. ”Noise from an analog (or small-signal) perspective...” ISBN 0-12-170960-4Teoksen verkkoversio.
Scherz, Paul: Practical electronics for inventors, s. 730. McGraw-Hill Professional, 2006. ”In order for analog devices... to communicate with digital circuits...” ISBN 0-07-145281-8Teoksen verkkoversio.
