Interpreters believe Nostradamus predicted the terrorist attacks
Sales of the Complete Prophesies and The Little Book Of Nostradamus, among others, have increased dramatically since Tuesday's attacks.
And, say Amazon, the sudden rise in sales is part of an general increase in interest in publications related to the disaster this week.
"It's one of those morbid business realities that in times like this people turn to relevant products," said Margaret Dawson, of Amazon.
Nostradamus was a French philosopher and astrologer who died in 1566.
He famously told tales of mass destruction and the end of the world, which people have been trying to interpret ever since.
The main reason for the increase in sales of the books seems to be that many believe he accurately foretold the attacks, particularly on New York.
Terrorism
But the tragic events of Tuesday have also put previously obscure titles related to the attacks on Amazon's list.
They include Fighting Terrorism by former Israeli prime minister Benjamin Netanyahu.
A history of New York's World Trade Center called Twin Towers, written by Angus Kress Gillespie, also entered the top 100 books this week.
Mr Gillespie said: "It's a very conflicted situation. To the extent that people can find comfort in the book, in a strange way it's satisfying."
Also proving popular is Hell To Pay, an unflattering book about Hillary Rodham Clinton by Barbara Olson.
Mrs Olson was a passenger on one of the hijacked planes and wife of US Solicitor General Theodore Olson.
American booksellers Barnes & Noble Inc confirmed on Thursday that it too had noticed an increase in sales about Nostradamus.
It also reported more books about Islam, and calendars featuring pictures of the World Trade Center had been leaving the stores.
"These are books that we ordinarily don't sell much of, so we're trying to keep them in stock," said a spokeswoman.