Even DC combined two features in "Superboy and the Legion of Super-Heroes" and had team-up books ("The Brave and the Bold", "DC Comics Presents" and "World's Finest Comics"). Virtually all such books disappeared by the end of the period. Marvel and DC worked out several crossover titles the first of which was "Superman vs. The Amazing Spider-Man". This was followed by a second Superman and Spider-Man, "Batman vs. the Incredible Hulk" and the "X-Men vs The New Teen Titans". Another title, "The Avengers vs. the Justice League of America" was written by Gerry Conway and drawn by George Pérez with plotting by Roy Thomas, but was never published, reflecting the later animosity between the two companies. Marvel editor-in-chief Jim Shooter was not pleased that DC wanted the fourth company crossover to include the New Teen Titans, DC's best-selling title at the time, as he wanted the crossover to be the X-Men and the Legion of Super-Heroes. This led to Shooter's decision to stall and cancel the JLA/Avengers project. Beginning circa 1970, Marvel introduced vast numbers of reprints into the market, which played a key role in their becoming the overall market leader among comic publishers. Suddenly many titles featured reprints: "X-Men", "Sgt. Fury", "Kid Colt Outlaw", "Rawhide Kid", "Two-Gun Kid", "Outlaw Kid", "Jungle Action", "Special Marvel Edition" (the early issues), "War is Hell" (the early issues), "Creatures on the Loose", "Monsters on the Prowl", and "FEAR", to name just a few. In the mid-'70s, DC launched numerous new titles such as Jack Kirby's "New Gods" and Steve Ditko's "Shade the Changing Man". Jenette Kahn would eventually take the helm of the company in 1976. The company followed this up in 1978 with the "DC Explosion" where the standard line of books increased in page count and 50 cent price. Many of these titles added backup features with various characters. However, DC greatly overestimated the appeal of so many new titles at once, sales dropped severely during the harsh 1978 winter and it nearly broke the company and the industry, including Charlton Comics; this event has been called the "DC Implosion". Marvel eventually gained 50% of the market and Stan Lee handed control of the comic division to Jim Shooter while he worked with their growing animation spin-offs.