Sidder, Gary B.Sims, P.K.2010-04-202010-04-201993Sidder, G.B. and Sims, P.K., 1993, Industrial Minerals-Today and Tomorrow: the Raw Materials to Build the Upper Midwestworkshop Proceedings, Minnesota: Minnesota Geological Survey Report of Investigations 42, 160 p.0076-9177https://hdl.handle.net/11299/60796en-USReport