With OPEN LICENSING, such as Creative Commons, the content creator continues to own the copyright of the content. By applying an open license to the content, they give permissions in advance to anyone using the content allowing certain uses without the need to seek permissions with each use.
Most common attributions are CC-BY-SA and CC-BY-NC-SA.
The Attribution is usually added to the title page or on a page before the Table of Contents.
Attributions Best Practices and Examples - Because there are various open licenses with OER, this is a good starting point for the do's and, sometimes, the don'ts of attribution.