The direct market is the dominant distribution and retail network for American comic books. The concept of the direct market was created in the 1970s by Phil Seuling. The network currently consists of: four major comic distributors: Lunar Distribution and UCS Comic Distributors (which distribute DC Comics since 2020), Penguin Random House Publisher Services (the distribution arm of the publishing company), which since 1 October 2021 distributes Marvel Comics and since 1 June 2022 distributes IDW Publishing (with Diamond switching to a Marvel and IDW wholesaler), and Diamond Comic Distributors, which distributes most, if not all, non-DC/Marvel/IDW comics (having exclusive deals with those publishers) the majority of comics specialty stores, and other retailers of comic books and related merchandise. The name is no longer a fully accurate description of the model by which it operates, but derives from its original implementation: retailers bypassing existing distributors to make "direct" purchases from publishers. The defining characteristic of the direct market however is non-returnability: unlike book store and news stand distribution, which operate on a sale-or-return model, direct market distribution prohibits distributors and retailers from returning their unsold merchandise for refunds. In exchange for more favorable ordering terms, retailers and distributors must gamble that they can accurately predict their customers' demand for products. Each month's surplus inventory, meanwhile, could be archived and sold later, driving the development of an organized market for "back issues." The emergence of this lower-risk distribution system is also credited with providing an opportunity for new comics publishers to enter the business, despite the two bigger publishers Marvel and DC Comics still having the largest share. The establishment and growth of independent publishers and self-publishers, beginning in the late 1970s and continuing to the present, was made economically possible by the existence of a system that targets its retail audience, rather than relying on the scattershot approach embodied in the returnable newsstand system. Comic book specialty shops Prior to the 1970s, most comics were found in newsstands, grocery, drug, convenience, and toy stores. A handful of early comic book specialty shops first appeared in the late 1960s, stocking back issues as well as sourcing new releases from newsstand distributors and the new counterculture underground comix. The oldest known such comics specialty shop in North-America (or worldwide for that matter) has been Canadian comic book store Viking Bookshop, established in Toronto by "Captain George" Henderson in the spring of 1966,