You can still find material prepared by Kasimir Bileski - the famous Canadian dealer - in auctions from time to time. Purchased a lot of France Sc 34 (Yt 30) recently and it came in hundreds of glassines with a little write up in each.
What I particularly enjoy is the Bileski marketing touch on these - the bulk of the lot is the very common cancels for this issue - e.g. "2145" GC (Lyon), "2240" GC (Marseille), Paris "1" star. But with his descriptions, every single glassine - no matter how mundane - is full of scarce and desirable cancels. A couple pictured below.