In 1966, de Camp made a deal with Lancer Books to republish the Conan series, which led to the "First Howard Boom" of the 1970s; their popularity was enhanced by the cover artwork of Frank Frazetta on most of the volumes. Many of his works were reprinted (some printed for the first time) and they expanded into other media such as comic books and films. The Conan stories were increasingly edited by de Camp and the series was extended by pastiches until they replaced the original stories. In response, a puristic movement grew up demanding Howard's original, un-edited stories. The first boom ended in the mid-1980s. In the late 1990s and early 21st century, the "Second Howard Boom" occurred. This saw the printing of new collections of Howard's work, with the restored texts desired by purists. As before, the boom led to new comic books, films and computer games. Howard's house in Cross Plains has been converted into the Robert E. Howard Museum, which has been added to the National Register of Historic Places.