This is a bit of literary scholarship for true bibliophiles. I compiled this list while reading Roald Dahl's 'Matilda' yesterday. This list of 23 books is 3 items longer than any previous version (moreover the version with 20 items had listed 3 books that are NOT mentioned in "Matilda").
The first 19 books are specifically mentioned in the text. The remaining 4 are reasonable educated guesses, although some other choices were obviously possible.
Rationale for last 4 books:
# "She went on olden-day sailing ships with Joseph Conrad. She went to Africa with Ernest Hemingway and to India with Rudyard Kipling."
# '"I am very fond of Charles Dickens," Matilda said. "He makes me laugh a lot. Especially Mr Pickwick." Duh! Too easy.