keyword: United States -- Discovery and exploration – 0 free books.
These OSI Approved License licensed ebooks are free to read - the people who created them want you to read and share them.
Open source licenses are licenses that comply with the Open Source Definition — in brief, they allow software to be freely used, modified, and shared. To be approved by the Open Source Initiative (also known as the OSI), a license must go through the Open Source Initiative's license review process.
These books do not seem to be included in the Directory of Open Access Books.
These books are available in MOBI format - good for Kindle.