Dave Spaulding, author of "Handgun Combatives", is a well-known figure in the world of firearms instruction and practical shooting. He's also a big fan of the Old West, both fictional and "factional", if I can put it like that.
Mr. Spaulding has published a three-article series on what really happened before and during the infamous Gunfight at the OK Corral in Tombstone, Arizona in 1881. In order, they are:
They provide a lot more information than the "usual sources", and are obviously based upon years of research and background reading. If the Old West interests you, I highly recommend these three articles. You'll find them fascinating.
(Mr. Spaulding's book is also well worth reading. Recommended.)