This was sent to me by Silversorcerer on the clarinetpages.info forum. Thanks, Silversorcerer!
from cyclopathic at Sax on the web:
Pruefer started clarinet company in 1906.
In 1914 he merged with Penzel and Mueller to form Penzel Mueller and Pruefer
In 1920 Pezel had died, Mueller gained control of the company and Pruefer retired
In 1920 Gus Pruefer had traveled to Markneukirchen, Germany and helped Moennig to modernize factory
1921 Restarted Pruefer clarinet company in US (young Hans Moennig joins Pruefer in RI)
1976 Factory in RI burned