No buttons - they're the sensors:
PagePress: To page forward or back in a book, squeeze either side of the screen. Use the line to page forward, and the dot to page back. You can keep your right or left thumb resting on the pressure-sensitive controls. To adjust the pressure required to turn a page, or the feedback you receive when a page turns, go to Settings, Reading Options then PagePress. You can also use PagePress to navigate your library on the Home screen.
