Acton, H. B. New Studies in Ethics: Kant's Moral Philosophy. London: Macmillan and Co., 1970, 71 p.
Critical and historical assessment of Kant's ethical philosophy.
Allison, Henry E. Kant's Theory of Freedom. Cambridge: Cambridge University Press, 1990, 304 p.
Interprets Kant's concept of freedom as it functions in his ethics and moral psychology, and surveys the secondary literature of the subject.
——. "Morality and Freedom: Kant's Reciprocity Thesis." The Philosophical Review 95, No. 3 (July 1986): 393-425.
(The entire section is 518 words.)