The Eternal Legacy of Treasure Island
https://www.britannica.com/story/the-eternal-legacy-of-treasure-island
This short Encyclopedia Britannica article explains some of the overall impact that Treasure Island has had over the years.
The Golden Age of Piracy
http://www.unmuseum.org/pirate.htm
This (admittedly rather antiquated) website provides resources for understanding the period of world history that immediately preceded the story of Treasure Island.
Richard Dury Archive of Robert Louis Stevenson
http://www.robert-louis-stevenson.org/richard-dury-archive/old-index.html
This website (which is also rather antiquated) provides a large number of resources related to the...