This list is not comprehensive, but it covers most of the conceptual bases I've run in this annotation.
Bakhtin, M.M. The Dialogic Imagination: Four Essays. Translated by Caryl Emerson and Michael Holquist. Austin: Unversity of Texas Press, 1981.
Bakhtin, M.M. Speech Genres and Other Late Essays. Austin: University of Texas Press, 1986.
Benjamin, Walter. "The Work of Art in the Age of Mechanical Reproduction." In Illuminations: Essays and Reflections, edited by Hannah Arendt, 217-251. New York: Schocken Books, 1968.
Herriman, George, Patrick McDonnell, Karen O'Connell, and Georgia Riley De Havenon. Krazy Kat : The Comic Art of George Herriman. New York: H.N. Abrams, 1986.
McCay, Winsor, and Richard Marschall. The Best of Little Nemo in Slumberland. New York: Stewart Tabori & Chang, 1997.
McCloud, Scott. Understanding Comics : The Invisible Art. 1st HarperPerennial ed. New York: HarperPerennial, 1994.
McCue, Greg S., and Clive Bloom. Dark Knights : The New Comics In Context. London ; Boulder, Colo.: Pluto Press, 1993.
Moore, Alan, and Dave Gibbons. Watchmen. New York, NY: DC Comics, 1986.
Morrison, Grant, and Frank Quitely. Flex Mentallo. 4 vols. New York: DC Comics, Inc., 1996.
Murray, Janet H. Hamlet on the Holodeck: The Future of Narrative in Cyberspace. Cambridge, Massachusetts: MIT Press, 1997.
Pearson, Roberta E., and William Uricchio. The Many Lives of the Batman : Critical Approaches to a Superhero and his Media. New York: Routledge, 1991.
Sabin, Roger. Comics, Comix & Graphic Novels. London: Phaidon, 1996.
Shaviro, Steven. "Chapter 1: Grant Morrison." Doom Patrols. 1997. http://www.dhalgren.com/Doom/ch01.html (4 July 1999).
Varnedoe, Kirk, Adam Gopnik, Museum of Modern Art (New York N.Y.), Art Institute of Chicago, and Museum of Contemporary Art (Los Angeles Calif.). High & Low : Modern Art, Popular Culture. New York: Museum of Modern Art ; Distributed by H.N. Abrams, 1990.
Wertham, Fredric. Seduction of the Innocent. New York,: Rinehart, 1954.
Witek, Joseph. Comic Books as History : The Narrative Art of Jack Jackson, Art Spiegelman, and Harvey Pekar, Studies in popular culture. Jackson: University Press of Mississippi, 1989.
Wolfman, Marv, George Perez, Dick Giordano, and Jerry Ordway. Crisis on Infinite Earths. 12 vols. New York: DC Comics, Inc., 1985-1986.