The central source for MT's first novel is obviously the childhood of Sam Clemens. But both Tom Sawyer the boy and Tom Sawyer the book are imaginatively dependent on texts. It is chiefly from books -- about Robin Hood, pirates, robbers -- that Tom gets his ideas about what and how to play. Tom is a very literal-minded reader, who goes devoutly by the book. As long, that is, as the book is not the Bible, but a romance of some kind. MT, on the other hand, is a realist re-writer. Although he accepted Howells' argument that Tom should be marketed as a "boys' book," and although generations of kids have enjoyed it as one, he wrote it more as a genial burlesque or parody of contemporary children's fiction.
The other texts in this section have been chosen to contextualize that project. Two are earlier satires by MT himself on conventional stories about boys -- his "Bad Little Boy Who Did Not Come to Grief" (1865) and his "Good Little Boy Who Did Not Prosper" (1870). In them he refers explicitly to Sunday-School stories. I haven't included any examples from that genre, but both Alger's Ragged Dick (1868) and Louisa May Alcott's Little Women (1868) are didactic enough to suggest the sort of story MT was trying to re-write, in them and in Tom. The March girls go by the book, too -- but their book is Bunyan's Pilgrim's Progress.
The other two selections here are from books that have often been suggested as sources for Tom. American readers first met Mrs. Partington's nephew Ike in the late 1840s. Aldrich's Bad Boy, also named Tom, made his debut in 1869.