As there appears to a current demand for resources on congressional oversight, executive privilege and the process for resolving executive-legislative disputes over information, I thought I would post a few suggestions as to places to look for such materials. First, there is this Congressional Investigations Research Page hosted by Georgetown Law (hat tip: Andy Wright). Second, the Congressional Oversight Manual has a list of selected readings starting at page 136. Third, Daniel Schuman has been collecting resources on the congressional oversight and subpoena power, particularly reform proposals.
Finally, here is a link to a 2002 brief filed by BLAG in Waxman v. Evans, which describes in some detail how executive-legislative information disputes have been resolved historically. To the best of my knowledge, this document has not previously been available on line.