David Parlett's page on Historical Card Games -- Parlett is one of the major games researchers, with a number of books under his belt. His website is broad (and much is out of our scope), but much of this page covers period games. (more)
Parlett on Piquet -- Goes into quite a bit of history, since this period game has more or less survived down the centuries; does not actually give the detailed rules. (more)
Parlett on Loo -- He has several reconstructions, and is looking at a broader sweep of history; I haven't yet checked his writeup against Cotton specifically yet. (more)