Complex sentence: In addition to fiction, Gissing followed his critical study of Charles Dickens with further writings including introductions to editions of Dickens'works, articles for journals and a revised edition of John Forster's biography of the author.
Split into simpler sentences: In addition to fiction, Gissing followed his critical study of Charles Dickens with further writings on him. This included contributing introductions to editions of Dickens'works, writing articles for journals and working on a revised edition of John Forster's biography of the author.