Okay, finally making some time to offer my contributions to the reference list.
I primarily collect Civil War Veteran materials. Here's a quick list of some titles that fill my reference shelf. I'll add others later when time permits.
A Collector's Identification and Price Guide for Grand Army of the Republic Memorabilia, Dennis M. Gregg, Full House Publications, 2005, 97pp. A good survey of the various GAR memorabilia - with estimated pricing.
Civil War Veterans' Organizations, Reunions, Badges, Turner E. Kirkland, Pioneer Press, TN, 1991, 32pp. A short but useful look at UCV & GAR organizations and memorabilia. Usually availble at shows or on eBay.
Union Civil War Veterans' Organizations in Maryland, Daniel Carroll Toomey, Toomey Press, 2004, 58pp. Fantastic information on Maryland Veteran Organizations. Great photographs! FYI, Daniel has a number of other publications focused on Maryland in the Civil War. If you're looking to learn about Maryland in the CW - his works are a great source!
Union Veteran Legion, 1884-1939, George G. Kane, Self-Published, 2005, 30pp. As far as I know the only book on the UVL - which was MUCH smaller than the GAR because of its strict membership requirements. At it's peak it only had 9,256 members. Available from George directly - or from him on eBay.
Organized Camps of the United Confederate Veterans, compiled by George G. Kane, self-published, 1997,90pp. A great reference for tracking down individual UCV Camps.
Wanted to throw this one in here - another of George Kane's books - United Spanish War Veterans (USWV). For the record - George's books are fantastic - printed on heavy-stock, in color usually, with an amazing amount of information. His works (and he has others I haven't listed here) aren't widely circulated because he self-publishes - which is a real shame because his works are very valuable references for collectors.
The History of the United Spanish War Veterans Through National Encampment Memorabilia, George G. Kane, 2005, 216pp. The ONLY reference on the USWV reference I've ever seen - I actually bought two copies because I was worried I'd wear-out my first copy using it constantly! I would rate this as the best Collector reference I've ever owned - seriously. It's fantastic reading - and a great reference book! In the interest of full-disclosure, there are a few items from my collection in this work <g>.
Badges and Ribbons of the United Confederate Veterans and the Sons of Confederate Veterans, Lynn jackson Shaw, 1989, 120pp. I actually have a second printing copy from 1996. All B&W photos but a great reference on UCV and SCV badges. You can find this one at most CW shows, and I've seen it on eBay before.
Membership and National Encampment Badges of the Grand Army of the Republic, 1866-1949, Kenneth R. Johnson and Jeffrey B. Floyd, Orders and Medals Society of America Monograph No. 11, 1997, 79pp. Photos of National Encampment Badges from 1866-1949, membership/attendance information for each Encampment, and general GAR Badge (membership) information.
The Southern Cross of Honor: Historial Notes and Trial List of Varieties, Peter Bertram, 2003, 59pp. If you want to know anything about the Southern Cross - this is the reference. Amazing number of detailed photos showing all the variations in the medal.
I hope you find these listings useful.
P.S. One of these days I hope to have a title or two listed on a list like this - with myself listed as the author. I've started a reference on UCV collecting - one of these days maybe I'll get around to finishing it!