All of our material is made available under the CK-12 Curriculum License or any noted third-party license. Adding copyrighted materials in your FlexBook® textbook is not permitted without the express permission of that material's copyright holder.
Content added to our platform by users is governed by our Terms of Use and shared publicly under the CK-12 Curriculum License. In particular, please note section 8 of our Terms of Use, though other sections do also apply.
It is your responsibility to ensure content you add to a FlexBook® textbook is available under a license compatible with our Terms of Use, or is your original work which you are willing to share under these same terms. All CK-12 content is licensed in similar ways to allow for sharing and derivations.