Full-text databases are wonderful for providing direct access to the articles themselves, but don't forget about indexes. Some of them contain some full-text (as noted), but they are also invaluable for tracking down the existence of an article when the citation that you are verifying is missing elements or has incorrect information.
Full-text access to legal research collections, including: Law Journal Library, Legal Classics Library, US Statutes at Large and Code of Federal Regulations (and other congressional documents), Treaties and Agreements Library, U.S. Supreme Court Library, English Reports (Full Reprint Edition) and more. All collections provide comprehensive coverage of each publication, with the a facsimile version of the full-text displayed in image-based format.