Directory of Open Access Journals
DOAJ defines open access journals as journals that use a funding model that does not charge readers or their institutions for access. From the BOAI definition  of "open access" we take the right of users to "read, download, copy, distribute, print, search, or link to the full texts of these articles" as mandatory for a journal to be included in the directory.
A work is in the public domain if:
- It is no longer under copyright - the term has expired
- It does not meet the requirements for copyright protection - ideas, procedures, methods, etc.
- The author elected to put the work into the public domain - many works with the Creative Commons license fall into this category
- It is a work of the United States government - may exclude the work of independent contractors