You might also read Why Coolidge Matters: Leadership Lessons from America’s Most Underrated President by Charles C. Johnson (New York: Encounter, 2013).
Coolidge and the Historians by Thomas A. Silver (Durham, NC: Carolina Academic Press, 1982) recounts the shoddy treatment Coolidge has received from historians. However, the book is hard to find and has become collectible and expensive.
Coolidge's own writings, especially the anthologies of his speeches are highly useful in understanding his political philosophy. These include The Price of Freedom (New York: Scribner's, 1924) and Calvin Coolidge: His Ideas of Citizenship as Revealed Through His Speeches and Writings (Boston: Wilde, 1924)
As much as I admire President Coolidge, that book left me hungry for more insight than he revealed. He lived up to his moniker of "Silent Cal" in that volume and perhaps his desire for privacy led to its terseness and lack of revelation.
That said, it does need to be on the bookshelf for those interested in this remarkable man. My suggestion is that it be read after a couple of others have first been digested, including those that Fiji Hill enumerated.
