If you are unsure whether the books were pre-ordered, check in your purchase history on your account page. Follow the steps below to verify that they were purchased (click on the images to enlarge them):
To view, cancel, or see the expected release dates for your pending pre-orders
1. Choose Store > View My Appie ID, then click Manage Pre-orders, which located in the Settings section at the bottom of the Account Information screen in iTunes on your computer.
2. From the Mange Pre-orders screen, click the Cancel button to the right of the pre-order item you would like to cancel. You'll be asked to confirm your pre-order cancellation.
You can find the full article here:
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