> Does anyone know of a reliable source that can help me verify some
> of these titles?
I'm sure Jessica Rosner is correct that no 100% reliable list exists.
But how reliable you need your info to be depends on your purpose.
If it's a research question: you want to write about films that have
fallen into the public domain, you would certainly be able to discuss
films that appear on several lists, with attribution: e.g. 'while
definitive information on copyright status is often elusive, and some
works can be brought back into copyright, these works are widely
considered to now be in the public domain.'
If, on the other hand, you want to DO something with the films: show
them, use bits of them as examples, or make found footage art out of
them, you probably have little to worry about anyway because: 1) your
purpose might be covered by Fair Use anyway, 2) as an academic you're
not really worth suing -- the attorneys have much bigger fish to fry.
Either way, a few things one might do to find out more about what is
and isn't PD.
Check the catalogs of Alpha Video and other distributors of ultra-
cheapo DVDs. I think all their titles are PD, especially anything that
has come out from several different distributors (e.g. Meet John Doe).
First, anything that is being distributed in this manner is
functionally PD, and second if some copyright holder shows up they'll
be going after these distributors, not anything you might have done
with the films.
If you have questions about specific titles that appear on one list or
another, especially for shorts, docs, industrials... check The
Internet Archive. Anything there is generally labeled with pretty
accurate rights info.
Finally, you can check the work of the Orphan Film people, Dan
Streible at NYU, and the programs of the Orphan Fiulm Symposiums. The
Orphan Film concept being works that are still in copyright but have
been abandoned or whose rights holders cannot be identified, the
'Orphanistas' have pretty good info on what's PD, and what's just in
Screen-L is sponsored by the Telecommunication & Film Dept., the
University of Alabama: http://www.tcf.ua.edu