To find the full text of law as it was passed by Congress, use Statutes at Large. HeinOnline includes links to the laws by their popular name.
If your law is not included in HeinOnline's list of popular names, the best thing to do is Google (or other search) the name you have for the law. Most quality articles about the law will include either the public law number or the Statutes at Large citation.
You can then search the Statutes at Large for that law using that number.
