Andy Warhol's artwork ranged in multi forms of media that include hand drawing, painting, printmaking, photography, silk screening, sculpture, film, and music. He was a pioneer in computer-generated art using Amiga computers that were introduced in 1985, just before his death in 1987. He founded Interview Magazine and was the author of numerous books, including The Philosophy of Andy Warhol and Popism: The Warhol Sixties. Andy Warhol is also notable as a gay man who lived openly as such before the gay liberation movement. His studio, The Factory, was a famous gathering place that brought together distinguished intellectuals, drag queens, playwrights, Bohemian street people, Hollywood celebrities, and wealthy patrons. Warhol has been the subject of numerous retrospectiveexhibitions, books, and feature and documentary films. He coined the widely used expression "15 minutes of fame". Much of his creations are very collectable and highly valuble. The highest price ever paid for a Warhol painting is US$100 million for a 1963 canvas titled Eight Elvises. The private transaction was reported in a 2009 article in The Economist, which described Warhol as the "bellwether of the art market". Warhol's works include some of the most expensive paintings aver sold.