Publications with status out of print are no longer available for sale. Major university libraries and the Library of Congress do have collections where you might find them. Publications with status general distribution document are free documents for which very limited supplies have been created. Increasingly, directorates at the OECD are posting them on the OECD Paris Headquarters web site. OECD's production of periodical issues is generally only marginally more than the number of subscribers we have, so supplies of back issues are generally very limited.
Check libraries for back issues.