For e-books and printed books, the same copyright is effective. Both can be acquired only for private or other single person use. Copies, reproduction or distribution is only permitted with explicit permission of the author or the publisher. The user is responsible for observing these law prescriptions and is liable for abuse.
If you cite a text literally, the author has to be mentioned - omitting this is a copyright infringement. Whole e-books must not be put on other websites for download.