Say for example that I want to know if the book "Catch-22" by Joseph Heller has ever been translated to Esperanto. It does not necessarily need to be available for purchase, or even ever been published. Is there a database somewhere that I can use, or how would I find out?
One possible way would be to contact the larger Esperanto libraries. Wikipedia lists them here.
The biggest collections of Esperanto literature are:
- The National Library of Austria (with the International Esperanto Museum).
- The Hector Hodler Library in Rotterdam, maintained by UEA.
- The Montagu Butler Library, maintained by the Esperanto Association of Britain.
The collection of The National Library of Austria has an online search which can be accessed here.
Jane Chen's suggestion is the best advice. However, this is a serious issue which is yet to be properly dealt with. To my knowledge there is no central database. Many old translations have never been reissued and it can sometimes be difficult even to persuade yourself of their existence (e.g. see if you can obtain a copy of The Odyssey in Esperanto). I am currently reading a recent translation from Korean which Google barely acknowledges.
Furthermore, there are unscrupulous people selling machine translations of famous novels on Amazon, and it seems that luckless beginners are buying them. It is natural to assume that Dracula has been translated into Esperanto, but it hasn't. The "translation" being sold there is a fake.
There have been situations in which someone completed a major translation and then left it unpublished. One recent example was La Pupo by Bołeslaw Prus.
In 2015, when Prus’s novel was the focus of the National Reading campaign, the Esperanto Association contacted Chmielik with a request for him to translate even a single chapter of the novel. It turns out, he had translated it all.1
It was published this year, as a 700-page book, after being in storage for 30 years. It is likely that there are plenty of manuscripts lying around that nobody knows about.