The books in the Center and Right are song books created by the Fujimoto group (a large organization of players and teachers, across a few different genres.)
They are for Min’yo (Book 6) and Hauta (Book 2).
The Left, Left of Center, and Right books are also music books, but not from Fujimoto.
Left is a book of Ryuukouka - essentially the predecessor of Enka and J-POP. It is the second anthology in its series.
The Left of Center book is a Nagauta book. This one is for the songs from Hanami-Odori.
The Right of Center Book is another Nagauta Book. EDIT: Found it! It’s for 松の緑 (The Green of the Pines).