Here are some of the books I've found enjoyable and of continued value in my journey through collecting and researching typewriters.

"Century of the Typewriter" by Wilfred A. Beeching.    This book was originally written in the early 1970's by long-time salesman and collector Beeching, and was first published in 1974.  A second, revised and altered version was published again in 1990 due to continued demand for copies.  This book gives what is, in my opinion, the best overall view of the whole world of typewriters -- as seen from the perspectives of history, of manufacturing, and of sales.  It is the best inside look at the industry  in the general reading field, but is very obviously directed at the collector and so provides quite easy reading.  It has been said that there are errors in the book, but these are few enough to be of little trouble.  Overall, this book is my top pick for "must have" for any typewriter collector.   I wish I had owned a copy during the first several years of collecting and researching, because the information in the book on modern portables fully supports what I've found independently with few differences.

"Antique Typewriters from Creed to QWERTY" by Michael Adler.  Originally published in 1977, this book is a Schiffer "price guide" in one respect only -- Adler gives rough prices.  Unlike other such books, though, this one is a huge fountain of information about antique typewriters, which helps a great deal in figuring out what machines were developed from what others, and gives a truly universal and world-wide approach.  Of great interest is his section of machine designs not produced, but much better is the wealth found in the following section on actually-built machines.  If you only bought one book on antique machines, this would be a top choice.

"The History of the Typewriter," subtitled "Successor to the Pen," by G. C. Mares.  This is a modern reprint of George Carl Mares' original 1909 work, which is likely still available from Office Machine Americana.  Post-Era Books republished it for the late Dan Post in 1985.  This is a wonderful look at early machines, including the first range of front-strike standards, as viewed from the perspective of those who bought and used the machines.  Much of the descriptive text about particular models liked by Mares reads like advertising copy, although Mares was also quick to point out faults.  This is a perfect snapshot of that point at which visible front-strike machines were entering the standard typewriter market, and is well worth reading for those who wish to acquire a perception of the competitive situation near the turn of the last century.

"Antique Typewriters & Office Collectibles - Identification & Value Guide" by Darryl Rehr.  This is, in one respect, almost fully and completely a "price guide."  Above that, though, it serves as what I still consider the best available quick-reference visual guide to antique machines.  My copy used to go everywhere with me simply because I could instantly find just about any antique machine I was likely to run across in the wild in it.  Like all price guides, the first obsolete fact is the prices, but this still ranks near the top in visual aids.  Extremely easy to use; descriptions laid out in concise language anyone can understand and get the most of.