Perhaps I was helped by not really knowing about US politics, because I started out not knowing what a Conference Report even was. I searched for "ADA documents", and after skipping a bunch of stuff about the programming language, found http://www.dbtac.vcu.edu/adaportal/ where I typed in "1990 conference report". This led to this page which included the phrase "the report of the Conference Committee, H.R. Conf. Rep. No. 596, 101st Cong., 2d Sess. 64 (1990)". Googling for bits of that phrase made it look as if such documents are often referred to in the form "101-596", and Googling "report 101-596" produced that PDF as the third hit.

Peter