John Markoff in his 2005 text, What the Dormouse Said: How the Sixties Counterculture Shaped the Personal Computer Industry referenced Kepler's as an important meeting point for the Counterculture of the 1960s [REF].
According to the 1992 book Aces Back to Back by Scott W. Allen, the roots of the Grateful Dead's musical family tree were sown at Kepler's Books in 1960.