148 pages. By Dean Hanscom, Historian, BTL. Covers topics from prehistory through the mid-1950s. From the author's introduction:

  This book lists important facts and dates for ready reference. It does not
elaborate and references are given only as sources for the dates indicated: other
and more detailed references may exist. With exceptions, 1956 is the closing date:
later advances must in general be covered in later editions.
   The references are (with only a few exceptions) to published articles and books.
All such publications are in Bell Laboratories Library, Historical Collection, or
files. References to original laboratory notebooks and files are not given. Different
authors sometimes quote different dates for the same event; I have tried to establish
facts or a weight of evidence from published sources, but in some cases there
are unresolved differences. In a book of this scope, some errors are inevitable.

Contributed by the Connections Museum.

768 pages, 80 MB, 500-468, A History of Engineering and Science in the Bell System - National Service in War and Peace (1925-1975). Missing pages 24, 25 and 504. Contributed by Sam Etler. Processed by Paul Fassbender

541 pages, 44 MB, 500-471, A History of Engineering and Science in the Bell System - Communications Sciences (1925-1980). Contributed by Sam Etler. Processed by Paul Fassbender.

825 pages, 83 MB, 500-473, A History of Engineering and Science in the Bell System - Transmission Technology (1925-1975). Missing page 566. Contributed by Sam Etler. Processed by Paul Fassbender.

370 pages, 8MB. A History of Engineering and Science in the Bell System - Electronics Technology (1925-1975). Copyright and First Printing 1985. Chapters on the Transistor, Silicon Integrated Circuits, Electron Tubes, Optical Devices, Magnetic Memories, Piezoelectric Devices, Relays and Switches, Capacitors and Resistors, and Thin-Film Circuits. Contributed, scanned and OCRed by Sam Etler. Cover, bookmarks and size reduction by Karl Brose. Processed by Paul Fassbender.

2,098 pages. Communication Engineering is concerned with the planning, design, implementation, and operation of the network of channels, switching machines, and user terminals required to provide communication between distant points.

This three-volume book is written for the practicing Transmission Engineer and for the student of transmission engineering.

Contributed and optimized for viewing on mobile devices by Karl Brose. Processed by Paul Fassbender.

902 pages. 48MB. Processed and Bookmarked by Steph Kerman.

1090 pages. 50MB. A History of Engineering and Science in the Bell System - The Early Years (1875-1925). First printing - 1975. Text searchable. Relatively low res images to keep file size low.  Find higher resolution images in the version posted on archive.org (about 380MB), but it is missing pages 446-7, 556-7, 664-5, 942-3 and 994-5. Processed by Karl Brose, Jack Ryan, Sam Hallas and Paul Fassbender.

687 pages. 36MB. A History of Engineering and Science in the Bell System.  Physical Sciences (1925 - 1980), 1983.   Contributed by Sam Etler, with post-processing by Clint Gilliland. 

652 pages. 34MB. A History of Engineering and Science in the Bell System.  Switching Technology (1925 - 1975), 1982.  Contributed by Sam Etler, with post-processing by Clint Gilliland. 

94 pages. 43MB. One of several issues published (and expanded) between 1958 and 1992. Contributed by Steve Cichorsky.  OCR by Clint Gilliland.