It really doesn't matter. 1877 is out of date in the scholarly world, period. It's out of date in my own thinking, just as William Patton's book is (1872). If one of my students did a paper on the subject and used either book as a source, I would count off just as I would for Wikipedia as a source.
I think you are wrong here! Wilson demonstrates a common usage throughout the eastern world for over a long period of time and that is not going to change simply because new materials are found. I would challenge you to read it as it has never been refuted, indeed, it is so thorough, no one has even attempted to refute it.