Here is a list of books related to American Barbizon and Tonalism. I have the first six books (actually five since the issue date of the book by David Cleveland is delayed). Some out-of-print books can be expensive, but check the local libraries or museums first.

Part 1 contains books of the movement or the school :

[asa book]0945936745[/asa]

[asa book]1555953026[/asa]

[asa book]1882897811[/asa]

[asa book]0300134061[/asa]

[asa book]0930295056[/asa]

[asa book]B000H0QC0K[/asa]

[asa book]B001RYSWZI[/asa]

[asa book]B0006F15HQ[/asa]

[asa book]B000OYSE4G[/asa]

[asa book]B001NM24LM[/asa]

And there is one more book “Barbizon Mood in France and America — European and American Paintings from the Brooklyn Museum of Art” which you can only find in the museum shop at the Brooklyn Museum. (NO ISBN for this book)