III, but the 1981 compilation was released with a color cover illustrated by Jim Roslof. Sutherland's interior artwork from the original two publications was included in the compilation, as was that of David A. Trampier. Other artists whose work appears inside the compilation include Jeff Dee, Erol Otus, David S. LaForce, Bill Willingham and Roslof. Vault of the Drow, also by Gygax and the last of the D-series, was also originally published in 1978 as a 32-page booklet with a two-color outer cover. The original printing featured monochrome cover artwork by David C. Sutherland III. In 1981, TSR re-issued the adventure with a new color cover. D3 was re-released to coincide with the release of the D1-2 compilation Descent into the Depths of the Earth. Since the D1-2 compilation featured color cover artwork, Erol Otus was tasked with creating a new color cover for D3 as well. Sutherland's interior artwork was retained, and other interior artists for the module include Jeff Dee, David S. LaForce, David A. Trampier, and Otus. The entire campaign was eventually combined into a supermodule GDQ1-7 - Queen of the Spiders. The modules were designed as a sequel to the G-series of modules. At the time these modules were released, each Dungeons & Dragons module was marked with an alphanumeric code indicating the series to which it belonged. The D in the module code represents the first letter in the word Drow. According to a Wired.com article, the D-series "introduced the world to the concept of the dark elves." Game statistics for the Drow first appear in the module, although the 1977 edition of the Monster Manual does mention the Drow.<ref>Gygax, Gary (1977,1978). Advanced D&D Monster Manual. TSR. p.39. .</ref> The D-series is part of a larger overall campaign of adventures set in the World of Greyhawk campaign setting. The overall campaign begins with the three modules in the G1–3 Against the Giants series, continues through the D-series, and concludes with module Q1 Queen of the Demonweb Pits. The latter segments of the campaign, including the D-series and module Q1, are set in a vast network of caverns and tunnels called the Underdark. The entire campaign was eventually combined into a supermodule GDQ1-7 Queen of the Spiders. Descent into the Depths of the Earth was the basis for a 2000 novel of the same title by Paul Kidd. The original TSR product codes for modules D1,