Shelley continued working on the play until his death on 8 July 1822. After his death, Timothy Shelley, his father, refused to allow Mary Shelley to publish any of Shelley's poems, which kept any immediate corrected editions of the play from being printed. Although reluctant to help the Parisian publishers A. and W. Galignani with an edition of Shelley's works, she eventually sent an "Errata" in January 1829. The Galignanis relied on most of her punctuation changes, but only a few of her spelling changes. The next critical edition was not released until 1839, when Mary Shelley produced her own edition of Shelley's work for Edward Moxon. Included with the edition were Mary Shelley's notes on the production and history of "Prometheus Unbound".