Some more research organizations and academia are Elsevier, Google Scholar, ScienceDirect, Pubmed, IEEE Xplore, National Agricultural Library (AGRICOLA), and Education Resources Information Center (ERIC).
There are also published government codes at house.gov and GPO Office (U.S. Federal Codes). Chances are likely that your state has online codes. Georgia likes to keep theirs on lexisnexis. Also check your county and city too. Also, check out Congress.gov as they are constantly publishing new codes.