Game Merchandising was a short-lived industry magazine for retailers/industry folks (see the "Not for Resale" on the cover) that existed from around 1981-1983, and earlier was a section of Model Retailer magazine. This time period that saw a boom in "gaming magazines", for example Ares (1980-1982, twelve issues), Adventure Gaming (edited by Tim Kask, 13 issues from 1981-1982) and Gameplay (edited by Jake Jaquet, another former Dragon magazine editor, 14 issues 1983-1984). The appearance of these were probably driven by the big sales of D&D during this time period. Another page from this same issue of GM puts the total units of D&D sold through 1982 at 2 million, and total units of AD&D sold at 1.5 million. The figure for D&D undoubtedly includes not only OD&D but also all of the Basic (Holmes and Moldvay) and Expert sets sold through mid-82.