Vannevar Bush's Atlantic Monthly article that some believe got the whole thing rolling
Bolter's Hypertext and the Convergence of Literary Theory is crucial -- he talks about how hypertexts function like scholarly work and compares it to the production of texts around the Torah by Jewish medieval scholars... if I remember it all right.
You should also check out Jim Sosnoski's work -- he's been working with the problem of the creation of databases as extended scholarly productions for, oh, about five years or so now.
Hypertext: The electronic labyrinth, Ilana Snyder, Melbourne University Press, 1996
Janet Horowitz Murray has a great text on narrative in cyberspace. She does consider hypertext as well as other cyberspace media. The text is _Hamlet on the Holodeck_.
George Landow's book Hypertext 2.0. I also like Gaggi's From Text to Hypertext. For something quick you might like Ilana Snyder's Hypertext Theory. That really gives a wonderful overview. Sven Birkerts, of course, challenges the literary-ness of hypertext in The Gutenberg Elegies. You'll find an somewhat different slant on hypertext (including an article that suggests hypertext writers create heirarchical overviews of their webs to assist readers) in Hypertext and Cognition edited by Rouet, Levonen, Dillon, and Spiro. I tend to throw this book across the room, but others seem to find it interesting. If you just want to look at a couple papers, you can read my comprehensive exam on hypertext theory (remember it's a comp and not the world's best writing) at
Jerome McGann's comparatively early "The Rationale of Hypertext." At least, it is a classic that students should read.