 He considered it "long overdue," citing "Language for Time Travelers" as "seminal" in "creat[ing] a permanent change in the way many time travel stories are written, or should be written" and "The Gnarly Man," "Nothing in the Rules" and "A Gun for Dinosaur" as "classics from which many subsequent stories by other writers have derived.... "Time after time, de Camp has created basic ideas which were obviously larger than his original setting, and whose development within the minds of other writers has given them a species of extended life, to the enrichment of the genre.