"Third Base" is a paper in American Scientist magazine published at 2001.

"Development of ternary computers at Moscow State University" by Brousentsov N. P., Maslov S. P., Ramil Alvarez J., Zhogolev E.A.

Introduction to Nondecimal Bases and description of The Balanced Ternary Number System

Very good introduction into balanced number systems with example on balanced ternary one.

Ternary hardware schemes on bipolar transistors (-1,0,+1 logic) and some theory (0,1,2 logic)

"Nikolay Brusentsov - the Creator of the Trinary Computer" by Boris Malinovsky

Francis Hunger, who was interested in the SETUN originally for the aspect of ternary computing, researched the archives of Columbia Universities libraries and has put together a detailed report on the attempt to copycat ternary computing technology from the Soviets through "Western" scientists.

The ternary calculating machine of Thomas Fowler was built in 1840 (first half of XIX century)!

The project is a proof-of-concept programmable trinary computer, that is, it uses three logical states instead of the two states common with digital computers today. The goal was to develop the trinary computer such that it is possible to play a game.

Introduction to Trinary (ternary) Computer Systems