Mary Shelley’s best-known book is Frankenstein; or, The Modern Prometheus (1818, revised 1831), a text that is part Gothic novel and part philosophical novel; it is also often considered an early example of science fiction.
Encyclopædia Britannica. (n.d.). Mary Wollstonecraft Shelley. Britannica School. Retrieved from https://school-eb-com-au.db.scotch.wa.edu.au/levels/middle/article/Mary-Wollstonecraft-Shelley/67263

Shelley, Mary Wollstonecraft, (1797-1851), was an English author. Shelley wrote the famous Gothic horror novel Frankenstein (1818).
Shilstone, F.W. (2024). Shelley, Mary Wollstonecraft. In World Book Student. https://www-worldbookonline-com.db.scotch.wa.edu.au/student/article?id=ar506040

Mary Shelley consolidated the Gothic as a particularly female form of novel. She deviated from the tradition in so far as her central character is not a woman. Mary based her novel on the latest discoveries in the sciences of her day. She created the genre of science fiction. Before publishing the manuscript, Mary gave it to her husband to edit; he made numerous revisions.
Rothwell, R. (2015). A Biographical Sketch of Mary Wollstonecraft Shelley (1797-1851). [online] victorianweb.org. Available at: https://victorianweb.org/previctorian/mshelley/bio.html.

Bringing the Author Forward: “Frankenstein” Through Mary Shelley’s Letters.
Carson, J. P., & Carson, J. B. (1988). Bringing the Author Forward: “Frankenstein” Through Mary Shelley’s Letters. Criticism, 30(4), 431–453. http://www.jstor.org/stable/23112085

The Project Gutenberg eBook, The Life and Letters of Mary Wollstonecraft Shelley, Volume I (of 2), by Florence A. Thomas Marshall
Marshall, F.A.T. (2011). The Project Gutenberg eBook of The Life and Letters of Mary Wollstonecraft Shelley, Volume I (of 2), by Florence A. Thomas Marshall. [online] www.gutenberg.org. Available at: https://www.gutenberg.org/files/37955/37955-h/37955-h.h