Two parallel series were John Gay and William Gay
Abbott's Boys, Non-fiction, and Miscellaneous Series are listed on a separate page, with links to available etexts.
The etexts of Harlie's Letter and Friskie at this site appear courtesy of Pat Pflieger. A complete bibliography of Abbott's works is available at Pat Pflieger's excellent Nineteenth-Century American Children and What They Read site. For a detailed study of the printing history of Abbott's books, with numerous illustrations and commentary, see Cary Sternick's Jacob Abbott website.