That's a really good question, because it comes up a lot. And the answer depends upon how much you want to get into it and out of it:

--really short thumbnail versions:

"The Civil War Dictionary" and "Historical Times Illustrated Encyclopedia of the Civil War" available at nearly all medium-to-large library reference sections or history reference sections will give you the down and dirty. These and others tend to be well researched and at this level errors are few. I am sure there are other quick-and-dirty one to five paragraph versions available in the reference section, but these are what I have used.

--read-in-one-setting slightly longer versions:

The one I use is Stephen B. Oates' 1961 "Confederate Cavalry West of the River" by the University of Texas Press, which covers what it calls "Price's Raid" in 15 pages with one of those being a useful map of the state of Missouri giving most of the routes of Price's various columns. If you are looking at a version and its fails to cover the different columns of Price's force, put it down! Oates' book is handy in paperback and widely available. Oates used this same format with similar maps for the other major Confederate raids into Missouri (Marmaduke's SW MO Raid of Dec. 1862-January 1863; Marmaduke's SE MO Raid of April-May 1863; and Shelby's Big Raid of October 1863), which makes this a really handy reference work. Scholarship has advanced with more primary and secondary sources since 1961, but Oates' version is good for its scope.

--longer works:

Watch out for the really old versons such as Britton's since he definitely has a dog in this fight and his prejudice shows, and the same goes on the southern side for John Newman Edwards' "Shelby and His Men." Just remember Edwards was Shelby's adjutant and loved really flowery prose as a newspaperman, too.

I think the other day somebody mentioned the "Blue & Gray" magazine version (Vol. 8, Issue 5, June 1991) which is 25 pages long (several of those are picture pages) and is written by Scott E. Sallee with acknowledgements to Marion B. Lucas, Richard Troutman, Albery Castel, and Orvis Fitts for assistance. This is most handy for me. Most detailed works about Price's Raid (or "Invasion," as some say) deal with only one battle or part of the raid such as Pilot Knob and the battles out west along the Kansas border, but other works about the whole thing include Castel's "General Sterling Price and the Civil War in the West," Castel's "War and Politics: The Price Raid of 1864" in the summer 1958 issue of "Kansas Historical Quarterly," that Sallee cites. Sallee cites others, too, including some about specific battles and/or organizations. I believe you can still purchase this copy as a reprint from "Blue & Gray," or find an old copy on Ebay and others.

If I want detail and accuracy (with limits) I dive into the "Official Records," but those many, many pages are disjointed reports by different commanders of various levels including Price, Rosecrans, Shelby, and just about anybody else who wasn't killed during the raid. Specifically, that is "O.R." series 1, vol. 41, part 1, pages 303 through 729 or 406 pages, if my math is right. Several recent replies to queries in this forum mention online versions and most middle to large libraries including college libraries have the paper verisons. The paper versions include the original set of 128 volumes of the "O.R." from the 1880s and 1890s and the 1985 National Historical Society new print which is easy to spot on the shelves with all those black books with gold spine lettering. I think Broadfoot Publishing out of Wilmington, N. C. still sells sets, too. I will let you in on a secret. You don't need all 128 volumes to study the CW in MO.

I am sure somebody else can mention other fine, detailed works, but this is what I use.

Bruce Nichols