This solid but accessible and clearly-written introduction to Kant's ethics draws at times heavily from Sullivan's more technical and comprehensive Immanuel Kant's Moral Theory (1989). The introductory work, however, fully stands on its own with one unfortunate exception: Only citations from the Foundations of the Metaphysics of Morals are referenced; with regard to all other citations from Kant's work, Sullivan states (p. 2) that the references can be found in the "relevant sections" of his 1989 work.
van der Linden, Harry, "Review of Roger J. Sullivan, An Introduction to Kant's Ethics (1994)" (1997). Scholarship and Professional Work - LAS. Paper 41.