Abel, Carl Friedrich: Grove Concise Dictionary of Music entry at WQXR radio focusing on his collaboration with J. C. Bach and his bass viol playing and composing.
Carl Friedrich Abel: Summary of musical style and output, biography, and portrait painting from the Classical Composers Database.
Classical Favorites: Carl Friedrich Abel: Short biography and a list of his most famous works.
Classical Music Archives: Abel: Sound files in MIDI format.
Great Books: Karl Friedrich Abel: Portrait and biography.
HOASM: Carl Friedrich Abel: A couple of portraits and a brief biography of the German composer and viola da gamba player. Includes a partial discography.
Karl Friedrich Abel: Free MIDI audio files from On Classical/Kunst der Fuge.
Wikipedia: Karl Friedrich Abel: Biography of the German composer.