- Millman & Taub, Pulse, Digital and Switching Waveforms. The classic textbook in this area; thorough on the discrete-transistor implementations of every multivibrator.
- A. Anand Kumar, Pulse and Digital Circuits. Clear, well-organized, lots of worked numerical examples.
- Horowitz & Hill, The Art of Electronics. Excellent on timers, Schmitt triggers, practical pulse-circuit design; the chapter on logic interfaces is the best single reference for mixing logic families.
- Lancaster, TTL Cookbook and CMOS Cookbook. Quirky 1970s/80s books, but full of practical wisdom about logic families that's still relevant.
- Maxim/Analog Devices/Texas Instruments app notes on the 555, on Schmitt triggers, on logic family interfaces. Free PDFs online.
- Walt Jung, IC Timer Cookbook. Hundreds of 555 circuits.
- Hans Camenzind's autobiography (free online) recounting how the 555 was designed in 1971: a wonderful glimpse into mid-20th-century circuit design.
section 11 of 111 min read