In addition to its annoying layout, this site bizarrely decides to mix public domain works from the various different major copyright systems together (life + 50 years, life + 70 years, the old American system of 95 years). For example, Nabokov's first novel in Russian, Mary, is listed because it was published in 1926; he died in 1977 which means in virtually every non-American country, that work will still be copyrighted until 2028.
They also include Jim Morrison who died in 1971, whose death is only relevant to the countries still on the life + 50 years system. However, it seems like very few of the Doors' songs give just Morrison songwriting credit. This means that only a small handful of Doors songs will be in the public domain in those countries and most likely this will not apply to the recordings either.
For American readers, the best way to find out what will be entering the public domain is to go directly to the Wikipedia pages for the "1926 in literature"[1], "1926 in film"[2], etc.