While a large number of mainstream-comics professionals both wrote and drew their own material during the Silver Age, as many had since the start of American comic books, their work is distinct from what another historian describes as the "raw id on paper" of Robert Crumb and Gilbert Shelton. Most often published in black-and-white with glossy color cover and distributed through counterculture bookstores and head shops, underground comics targeted adults and reflected the counterculture movement of the time. The Silver Age of comic books was followed by the Bronze Age. The demarcation is not clearly defined, but there are a number of possibilities. Historian Will Jacobs suggests the Silver Age ended in April 1970 when the man who had started it, Julius Schwartz, handed over "Green Lantern" – starring one of the first revived heroes of the era – to the new-guard team of Denny O'Neil and Neal Adams in response to reduced sales. John Strausbaugh also connects the end of the Silver Age to Green Lantern. He observes that in 1960, the character embodied the can-do optimism of the era. However, by 1972 Green Lantern had become world-weary, with the character saying in one story, "Those days are gone – gone forever – the days I was confident, certain ... I was so young ... so sure I couldn't make a mistake! Young and cocky, that was Green Lantern. Well, I've changed. I'm older now ... maybe wiser, too ... and a lot less happy." Strausbaugh writes that the Silver Age "went out with that whimper". Comics scholar Arnold T. Blumberg places the end of the Silver Age in June 1973, when Gwen Stacy, girlfriend of Peter Parker (Spider-Man), was killed in a story arc later dubbed "The Night Gwen Stacy Died", saying the era of "innocence" was ended by "the 'snap' heard round the comic book world – the startling, sickening snap of bone that heralded the death of Gwen Stacy." Silver Age historian Craig Shutt disputes this, saying, "Gwen Stacy's death shocked Spider-Man readers. Such a tragedy makes a strong symbolic ending. This theory gained adherents when Kurt Busiek and Alex Ross' "Marvels" miniseries in 1994 ended with Gwen's death, but I'm not buying it. It's too late. Too many new directions – especially [the sword-and-sorcery trend begun by the character] Conan and monsters [in the wake of the Comics Code allowing vampires, werewolves and the like] – were on firm ground by this time."