How can we determine if books in public domain have been translated into a given language?
I know that some helpful websites exist.
Several sources exist to translations of the Bible is many languages.
The Protestant Reformed congregation in Ulster has a listing and links to a multitude of translations of the creeds and reformed confessions and some of their reformed literature.
Languages
Various Anglican links provide links to translations of the Book of Common Prayer, which include the oecumenical creeds and in many cases the 39 Articles.
What about books that are in print but not on the web. For instance how can I find out if Owen's Death of Death in the Death of Christ has been translated into Thai? Or how can I determine if Ryle's Expository Thoughts on the Gospels has been translated in to Nepalese or Burmese? Is there a list someplace? An international list of books in print?