"M. Wattenberg. A note on space-filling visualizations and space-filling curves. In Proc. IEEE Symp. Information Visualization (InfoVis), p 181-186, 2005."
I quote Ullman's section on "Avoid non-referential this":
While it sounds pedantic at first, you get a huge increase in clarity
by chasing the "nonreferential this" from students' writing. Many
students (and others) use "this" to refer to a whole concept rather
than a noun. For example: "If you turn the sproggle left, it will
jam, and the glorp will not be able to move. This is why we foo the
bar." Now the writer of this prose fully understands about sproggles
and glorps, so they know whether we foo the bar because glorps do
not move, or because the sproggle jammed. It is important for
students to put themselves in the place of their readers, who may be
a little shaky on how sproggles and glorps work, and need a more
carefully written paragraph.
Source: Jeffrey D. Ullman, Advising students for success, CACM 52(3):34-37, March 2009