stereoviews: old stereoscopic view cards wanted

I collect old stereoviews and will travel to purchase them. They are also known as stereopticon (a misnomer but a term many people know them by). I am especially interested in a local stereo photographer named L. Hensel. I will purchase single cards or whole collections, and boxed sets. All subjects and dates, flat cards and curved cards. I will also purchase stereoscopes (a.k.a. stereopticon) and Beckers and other table top or floor model stereoscopic viewers. See the pictures. Thanks. Dave, Milford, Pa.