Unknown first publication

[MarkThiel]

I have a scan of a trio by Frederic Duvernoy (1765-1836), a composer who has been decomposing for long enough to satisfy most copyright laws, I think. The edition says "1965 World Copyright by EDITION KaWe - Amsterdam". So is this legal ? Is there any presumption of publication in Duvernoy's lifetime or does one actually need to demonstrate that there is a pre-1923 published edition ?

[Carolus]

The 1965 edition is non-urtext and contains much original material from the editor, who died in 2003. (You already know all of this now via our contact on the wiki, but I am posting here too so others can see). Even if first publication was in the composer's lifetime, the derivative work in this case is protected for the editor's life plus 50 or 70 years (publication plus 95 years in USA).