Fritz Langford-Smith was the author of "Radiotron Designers Handbook" (or "Radio Designer's Handbook") which was often called the "bible" of vacuum tubes and their circuits, it was also sometimes known as "the big red book".
Fritz Langford-Smith was the author of "Radiotron Designers Handbook" (or "Radio Designer's Handbook") which was a classic engineering reference book released in different versions over the years. It was often called the "bible" of vacuum tubes and their circuits, and also sometimes known as "the big red book".