A couple of journal articles to get at the library:
Klien, Mia. “The “Other” Beauty of Martin Luther King, Jr.’s “Letter from Birmingham Jail.”” CCC 32.1 (1981): 30-37.
Submits that Martin Luther King’s persuasiveness in his writings may be attributed not only to his structure, logic, and ethos, but even more to his creative, eloquent, and commanding use of the English language. Supports this argument with examples from King’s “Letter from Birmingham Jail.” (RL)
Walker, Jeffrey. “The Body of Persuasion: A Theory of the Enthymeme. College English 56.1 (1994): 46-65.
Examines the primary and not exclusively Aristotelian sources from which a more adequate concept of the enthymeme can be derived. Considers the relevance of that concept to the analysis of modern discourse. Analyzes works by Martin Luther King, Jr., and Roland Barthes as examples of enthymeming. (HB)