How to Identify collectible glassware from the 1940 s to the 1970 s

3 glaze flakes on rim, see photos 10-11 for closeups. Although unmarked, this is an early piece from Pouplard-Beatrix from the very early 1900's and one of the designs featured in Leon Pouplard (PBx) book by Champion & Kervella, see last photo.