Apple sold 350,000 textbooks in three days after making them available on its iBookstore, figures from a U.S. research firm show. Global Equities Research, which said it monitors textbook downloads through its own \"proprietary tracking system,\" has recorded the sales since Apple Apple unveiled digital textbook support for its iPad last week, Cnet reported Monday. The textbooks, with video, 3D images and the ability to add notes, sell for as little as $14.99, far less than traditional textbooks. Major textbook publishers are still making a profit selling through the iBookstore, analysts said, because the direct-to-consumer option cuts middlemen distributors and production costs. Apple also announced iBooks Author, a Mac OS X application intended to aid authors in publishing interactive iBooks and textbooks. Global Equities Research said iBooks Author was downloaded 90,000 times during its first three days of availability.