Sor’s Souvenir de Russie op. 63 for two guitars is his last work, and a magnificent one. It is based on two Russian melodies, and was first published in Paris in 1838-39.
You can hear it here played splendidly by Claudio Maccari and Paolo Pugliese.
The beginning of the main theme is FREE TO EVERYBODY.
This edition comes from the new 2020 second edition of Sor’s New Complete Works for Guitar edited by Brian Jeffery. The Introduction and Index to the entire series can be seen here on this site.