Link on online library
 https://ebooks.adelaide.edu.au/s/shelley/mary/   You can read there:         History of Six Weeks' Tour through a Part of France, Switzerland, Germany, and Holland,with Letters Descriptive of a Sail round the Lake of Geneva, and of the Glaciers of Chamouni [1817]  Frankenstein; or, The Modern Prometheus [1818, 1831]  Mathilda [1819]  Valperga; or, The Life and Adventures of Castruccio, Prince of Lucca [1823]  The Last Man [1826]  Lodore [1835]  Falkner [1837]  The Poetical Works of Percy Bysshe Shelley [1839]  Proserpine & Midas: two unpublished Mythological Dramas / edited with an introduction by A. Koszul