I have a copy of the book, picked it up in April. Very well done in my opinion, well researched and up to date (as of spring '09 I believe). Takes each unit and provides the sources for information (I guess that's why it's a Bibliography!)
Mr. Pearson teaches Civil War History Classes through the St. Louis Public Library, as well as Genealogy Classes, and he's a (hope I get this right) Reference Librarian for the StLPL.
I got the copy for use 'down the road' when I have time to research my mother's side of the family (maiden name "Price"--yes, we're coattail relatives according to my 93 year old great aunt).
You can preview the first 12 pages of the book at lulu.com, search under "Missouri State Guard" and it comes up. In the preview, you only actually see the first page of the actual bibliography, but you can see the table of contents though.
Hope that helps.
Frank 'Skip' Arensmann