2 excellent books on glass costume jewellery/beads are "Glass in Jewellery" & "Baubles,Buttons,& Beads" by Sybille Jargsdorf, a German writer/researcher.
Lots of info on the beadmakers of Bohemia & Germany,& also Venice.
Most of the beads & other components(metal fittings) used in costume jewellery in 19th-20th C. came from Bohemia.
These weren't usually marked with makers names, however designer or importers names were often added, even if they had little or no input in making the items.