The title is "Gregg Expert Speed Building", by Charles Zoubek. The Diamond Jubilee version is copyrighted 1968. From the preface, " 'Greg Expert Speed Building' is designed to enable the student to reach speeds beyond 120 words a minute. To help him achieve these speeds, the text provides approximately 200 Expert Shortcuts for frequently used business expressions and phrases, shortcuts that will be of tremendous value to the student after he automatizes them."
These "expert shortcuts" in fact are a new set of brief forms. For example, in the first lesson the following are provided:
cover (blended kay-v)
appropriate (a-pr-a)
employ (m-p)
insure, insurance (n-ish)
administer (a-min-e-s)
application (a-pl-ish)
It would be interesting to study and see how many of the "expert shortcuts" are actually just the re-introduction of brief forms from earlier versions of the system.
There's also an emphasis on "expert shortcut derivatives", and some advanced word-building principles (such as "the dot for 'h' may be omitted in the following words: has, him, himself, had, her, whether").
The book has lots of "expert speed pointers" as well.
Anyhow, it may be something worth watching for on e-bay, or looking for at abebooks.com or at other used-book dealers.