Koussevitzky piece still not in the public domain?

[ya89]

I assume the following piece (see link) must be written before 1900 and, as far as I know, this score is an original composition, i.e. not an arrangement someone else made.
Could someone please clarify why it says it is Non-PD in the US? Or, is it a mistake?

https://imslp.org/wiki/Humoresque,_Op.4 ... ky,_Serge)

[DBMiller]

The date when a piece was written is not usually important for US copyright. The details of publication are usually what's relevant. Some works aren't published until many years after being written.

Since this piece was, to my knowledge, first published in 1936, when Koussevitzky was not yet a US citizen (he became one in 1941), and first published in the Soviet Union and not the US, and since the work was created when Koussevitzky was not a US citizen, this item is probably URAA-eligible, and thus will not enter the public domain until 2032 (after a 95-year term counting from the initial publication in 1936).

[cypressdome]

I've updated the page with the reference to the first edition which was published by Jurgenson in Moscow in 1907.

[DBMiller]

If first published in 1907, then this piece is PD-US. Thanks!

[ya89]

Much thanks to both of you for this clarification!