Publisher's Weekly reports the death of Peter Beren, 75, on June 28.
"Beren began his career in 1976 as an editor with the San Francisco indie publisher And/Or Books, but was best known for his work at Sierra Club Books, which he joined in 1988 as marketing director, and where he rose to the position of publisher, which he held until his departure in 1997," the obit says.
It also says, "During his 'retirement career,' which he wrote about for PW in 2014, Beren continued to champion Bay Area figures, working with such talent as photographers Art Wolfe, Frans Lanting, Galen Rowell, and Baron Wolman, as well as scholars Ralph Metzner, Colin Wilson, and Robert Anton Wilson (no relation)."
The Wikipedia article on And/Or Press says that the publisher put out two Robert Anton Wilson books, The Illuminati Papers (1980) and Right Where You Are Sitting Now: Further Tales of the Illuminati (1982).
Beren's official page lists books he has written, including More True Than Strange: Collected Writing 1968-2018. The book's description includes this sentence: "Meet Gurus like Karmu, the Black Christ of Cambridge, Timothy Leary and his sometime collaborator, Robert Anton Wilson, musicians like the Incredible String Band and Canned Heat, or some of the famous chefs, like Alice Waters and Bruce Aidells, who started the Foodie Movement."