Here is the list of books related with the series 'The Lord of the Rings', in order of publication:

1. The Hobbit 
2. The Fellowship of the Ring 
3. The Two Towers 
4. The Return of the King 
5. The Silmarillion 
6. Unfinished Tales of Numenor and Middle-earth 
7. The Children of Hurin 
8. Beren and Luthien 
9. The Fall of Gondolin 