From the webpage:
Retrieve legislation (amendments, bills, laws, and resolutions) or committee reports by specifying the congress number, the document type abbreviation, and the document number (e.g. 114hr1, 113s.rpt.25, 104PL104). Citations work with or without spaces and periods, and in upper or lowercase. All supported citation formats are listed at Search by Number.
Alternatively, specify a congress using the checkboxes below and search legislation within that congress (e.g. H.R. 202, s744, ha70, S.Amdt.250, pl113-2).
A new way to search for legislation, reports, etc. from the U.S. Congress.
Especially helpful when reading articles whose authors haven’t mastered the art of hyperlinking to congressional materials.
BTW, from Congress.gov Advanced Search, I created a one pager on congressional citations. I had to use 10pt type to get it all on one page but can post the source if you want to produce it in a different size.