C19 includes the reference work, Dictionary of Nineteenth Century Journalism, where you can look up individual magazine titles to learn about their audience, writers and editors.
Results are divided into six possible sections, based on the indexes searched: books, periodicals, official (government) publications, archives, newspapers, and reference works.
Books:
Nineteenth-Century Short Title Catalogue; The Nineteenth Century publishing program,
Periodicals:
ProQuest’s American Periodicals; ProQuest’s British Periodicals; Cotgreave's Index; An Index to Legal Periodical Literature; Cumulative Index to Niles' Register, 1811–1849; Periodicals Index Online; Poole's Index to Periodical Literature; Stead's Index to Periodical Literature; The Wellesley Index to Victorian Periodicals, 1824-1900
Official Publications:
House of Commons Parliamentary Papers; Proceedings of the Old Bailey; The U.S. Serial Set
Archives:
Archive Finder
Newspapers:
Palmer's Index to The Times
Reference:
The "Bookman" Directory of Booksellers, Publishers and Authors; Dictionary of Nineteenth Century Journalism