Adding the initial http links it automatically:
Heh, fixed mine to save somebody yet one more second. Wrote this comment to waste that second that I saved.
That said, I'm reading this paper now. It's absolutely fascinating and very approachable. Well worth checking out.
The link is returning a 403 now (perhaps too much traffic from this article).
For anyone that still wants to read it, here's a citation -- you can easily find a copy by searching for the title of the paper.
Bacon, David F., Perry Cheng, and V. T. Rajan.
"A Unified Theory of Garbage Collection."
Convergence 6, no. 17 (2004): 32.
http://www.cs.virginia.edu/~cs415/reading/bacon-garbage.pdf