We have two copies of this rare monograph in our collection.

We know of only one other copy. It was part of the famous Origins of Cyberspace auction at Christie's in 2005. But I suspect there are a couple more buried in the basement of a physics professor, an engineer or a mathematician. (I doubt it's tucked away in the bookcase of any communication professors...one look at the extensive number of formulas would have scared them off.)

There is also a similar monograph by Shannon from this same time period and same publisher (Bell Systems). It is entitled Communication theory of secrecy systems. It was Shannon's groundbreaking work in the area of code breaking. We have one in our collection.

For more information, click on the link(s) below.
     Christie's Auction House

     Manhattan Rare Book Company in New York, USA

If you know the location of any other of these, please let us know by contacting us at info@EarlyComputers.com.