Facebook CEO Mark Zuckerberg’s new book club, “Year of Books”—which unveils a new title every two weeks—has sent publishing houses into a frenzy. Because Zuckerberg alerts club members of his new selection without letting publishers know his selections in advance, publishers must rush to ship print copies to stores.

Thirteen thousand copies of the first book, Moises Naim’s The End of Power, flew onto shelves just a week after Zuckberg made the selection, 10,000 of which were e-books. Perseus Books Group CEO David Steinberger said that the initial supply of digital copies allowed the house just enough time to get out 30,000 print copies within a week to meet the demand.

Likewise, Penguin Books had to get out 12,000 print copies of Zuckerberg’s recently announced second selection, Steven Pinker’s The Better Angels of Our Nature, before the end of the week.

Still, Penguin Books’ president and publisher Kathryn Court is optimistic. She admitted that “in an ideal world,” publishers would have advance notice about Zuckerberg’s selections; however, the club still means great business for publishers. It’s “great to have [him] promoting books,” she said.