InterDok has announced that it is offering the Directory of Published Proceedings (DoPP) freely available on the Internet. DoPP indexes published conference proceedings in science, engineering, medice, social science and humanities. There are over 280,000 records available.
InterDok does also offer an Acquisitions Service if you wish to purchase any of the indexed proceedings. But, before you do that, check out your local library. Even if they don’t have them, they might be able to interlibrary loan them for you.