The question often arises, "What is an acceptable reference
for a paper?" In my classes, there is one important rule. For references
you wish to use that are posted electronically, the format of the cited work
should be either PDF or Postscript,unless you get specific approval for some
other format. This means that in general, HTML files are not appropriate as
references. This rules out, in particular, citing Wikipedia or Mathworld. These
are often outstanding places to begin your search for references, but you should
not end your search there.
