New St. Basil Hymnal: Public domain, or not?

I've looked up the previous discussions about the New St. Basil hymnal, and saw in one that it was stated that this hymnal has expired copyright, so it's now in the public domain. However, you can order new copies of it through Hal-Leonard company, or sheetmusicplus.
So has anyone done the legwork already, and can tell me officially whether the music in this hymnal can be copied, or not?

We are thinking of selling our copies of the full hymnal , but there's about 25 hymns I would want to keep for supplemental use in the parish.


Thanks!