To facilitate legal research, companies, such as Thomson West, provide subscription-based online information-retrieval systems. Seeking to improve these and related IR systems, the present inventors recognized researchers often overlook some types of documents, such as legal encyclopedias and treatises that may be useful to them. Accordingly, the present inventors devised systems, methods, and software that automatically search for other types of documents not specifically targeted by user queries. One exemplary system automatically submits a user query for legal opinions to first and second databases, with the first storing legal opinions and the second storing non-opinion documents, such as headnotes from the West Key Number System, articles from American Law Reports, and/or articles from American Jurisprudence.