For the casual Cinderella collector (such as myself), I never realized until recently that during the 1930s to the 1950s there was a publication "The Poster Stamp Bulletin" published with news about poster stamps when they were very popular.
I found this resource helpful as I can actually download (in jpg format) individual pages of interesting material from many editions of that publications, so I thought I'd share the link for anyone who may be interested:
http :// alphabetilately . com / PSB-index.htmhttp://alphabetilately.org/<<Updated link from W. Senkus, owner of the website. KirkS 1Aug13>>