: Sites like Art Song Central provide clean, printable PDFs of "‘O Sole Mio" in various keys suitable for students and performers.

Because specific file links change or require purchase, here is how to reliably find the sheet music:

" is arguably the most famous Neapolitan song in the world. While it is often performed by high tenors (like Pavarotti) in its original key, it is a staple in the repertoire of low voices (basses and baritones) as well.