KevH Glass Pages have a series of articles written by KevH about Ysart family paperweights and related items.
http://www.btinternet.com/~kevh.glass/
They include:
Inkwells - "Monart", "Vasart" or "Other"?(Probable!) "Vasart Ltd" Mixed ConcentricA Rare "Harlequin" WeightCatalogue of Ysart PaperweightsFake Paul Ysart PaperweightsPaperweights (and Related Objects) by Paul YsartSalvador Ysart & Ysart Brothers Glass PaperweightsPaperweight Attributions Vasart and Strathearnand some very useful links to glass information on other websites.