This looked interesting, so I got it inexpensively. The information inside says copyright 1973 by Voncorp, Dunedin Florida. This item is number 116 of ??. The sheet is numbered on the back, so, apparently, a limited edition. The front, inside cover, and actual examples are shown. Any others out there to show?
The Philatelic Educational Cards (PECs) were created and marketed by the husband and wife team of Paul and Donna Von Stein, a couple (in every sense) of stamp dealers in Dunedin Florida doing business as "Voncorp." In addition to the PEC card series as described above, they created other philatelic educational tools such as Graphi-Guides (for identifying U.S. stamps by issue and type), Milli-Vu, Perf-Vu, Phila-Tiques (for use as awards), and, my personal favorite, the philatelic journal "Strictly U S ..." I never bought any of their educational products, but I did subscribe to their journal and have kept a complete run of it to this day. It is still a useful resource for my purposes to this day, and a personal memento to me from Donna.