By definition, an open textbook is open because the author has decided to share their copy rights with others. This decision is indicated by posting a statement, and sometimes logo, describing the open-copyright licence — most often a Creative Commons licence. (See Creative Commons licences.)
Other times, the author chooses to release or designate their copy rights to the public domain. Creative Commons has created two public domain tools for authors who select this option. (See Public domain tools.)
Creative Commons Information Pack
The National Copyright Unit and Creative Commons Australia have jointly developed the Creative Commons Information Pack [New Tab] for teachers and students on Creative Commons (CC). The pack explains what CC is, how to find CC material, and the best way to attribute CC material.
Combining CC licences
This video, Creating OER and Combining Licenses-Full [YouTube – New Tab], was created in 2012 by TheOGRepository. It aims to help you choose compatible resources and choose a valid licence for your work.