Missa "Adéste fidéles" : for S.A.A. or T.B.B. with organ: New York : J. Fischer & Bro., ©1944. Or in English published Fischer 1966 (2?3? voices), 1967 (SATB)
Carlo Rossini (1890-1975), an Italian priest and composer, working in Pittsburgh, United States of America.
So presumably still in copyright, but I can't find them available anywhere.
OTOH the Propers are available on this CMAA site, and elsewhere.

Yes, renewed 2Aug72, R533992.

Well, we can wait three years then and re-evaluate whether it merits rediscovery or should go sit in the corner with Mass of the Shepherds. Thanks to all.

I think USA has 95 years, and 70 years from death of the author, so 2039 or 2045 (whichever is later). But I am neither expert nor resident of USA.

Ha!! 95 years in this case. Thx, R Mix

If it's not in print, it wouldn't hurt to ask the owner how to get a copy. They may be willing to copy something from their files and sell that to you.

I see this Mass has been used by the church of St Margaret Mary, Oakland, CA. One could try contacting the DM, David Sundahl.
Towards the bottom of this page there are recordings they made in 2009. Personally I am not impressed by the SATB setting, perhaps the others are of use.

It is though, deplorable if your law has been so written that it now frustrates the desire of the author, which in this case was to enhance the liturgy AMDG, as directed by Tra Le Sollicitudini.

your law has been so written that it now frustrates the desire of the author, which in this case was to enhance the liturgy AMDG

I would assume that all composers writing liturgical music have the good intention to enhance the Church's liturgy, even if they are so lacking in the craft of musical composition that they really should not be writing for the liturgy. I'm also convinced that Fr. Carlo Rossini composed for the glory of God. But I'm also convinced that he probably received the highest royalties of any Catholic composer in the USA (or was second only to Nicola Montani) during the years he was composing that music. I would also hazzard to guess that were he still alive today Fr. Rossini would be happily surprised that his Missa Adeste Fideles is still under copyright; I doubt that such would frustrate him or any desire he would have.

There is nothing immoral or illegal about copyrighting one's intellectual properties or receiving royalty for the distribution of said properties.

incardination, you are quite right. Thank you.

But let's not overlook the fact that someone (perhaps the Diocese of Pittsburgh, or a relative of Fr. Rossini) inherited his musical contracts when he died. And what that heir chooses to do (e.g., either demand that Carl Fischer or its successor make the Mass available for purchase - as it contracted with Fr. Rossini to do - or, desiring to be freed from that obligation, cede the copyright back to the heir so that said heir can determine how to provide for the future availability of the music, etc.) is the heir's business to pursue or not pursue, whether we like it or not.

I'm sure this situation happens all the time with music still under copyright but out of print from a publisher with no plans to reprint it.

Apparently the same problem--lack of heir's action--has kept the "Roger Wagner" arrangements out of print for quite some time, too. The heir was, at one time, selling cassettes of the Chorale's recordings, but they are not easy to get anymore; and CD's are not available, period, with a very few exceptions.