Over the past few months, we've seen major publishers hold back the electronic book version of popular titles, including the Sarah Palin and Edward Kennedy memoirs and Stephen King's latest novel. Now two publishing houses are expanding that policy, telling the Wall Street Journal they'll delay a raft of books from going digital by up to four months after the hardcover release.

It's a sign that parts of the book publishing industry are hardening their opposition to the widespread retailer practice — spearheaded by Amazon.com — of selling electronic versions of new release books at a heavily discounted $9.99.

Simon & Schuster and Hachette Book Group are the two publishers delaying more titles. Simon & Schuster CEO Carolyn Reidy told the Journal that the "right place for the e-book is after the hardcover but before the paperback," acknowledging that some readers will be "disappointed" by that timeline. Upcoming Simon & Schuster titles affected by the new policy include Don DeLillo's "Point Omega" and the Karl Rove memoir "Courage and Consequence."

Many book publishers want to avoid a scenario where e-books eat into sales of more expensive hardcover releases, which typically have a list price in the mid-$20s or higher. While the publishers don't necessarily lose money themselves when a retailer discounts individual e-books, they fear that the current $9.99 standard for digital titles will create a "sticky" price in people's minds that will upend the publishing industry's business model.

Amazon is pushing hard for simultaneous release of books in hardcover and for its Kindle reader, with a company spokesman issuing this warning via the Journal: "Authors get the most publicity at launch and need to strike while the iron is hot. If readers can't get their preferred format at that moment, they may buy a different book or just not buy a book at all."

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