A week and a half ago I mentioned the bit in The Real Frank Zappa Book where he talked about how he first discovered Edgard Varèse.
Well, it's been about a decade since I read the book, but I just ran across an article called Edgard Varèse: The Idol of My Youth from the June 1971 issue of Stereo Review, and I'm pretty confident it's the same piece. (If it's not, it's a different telling of the same story.)
Another Zappa interview courtesy of afka.net.