I bought 4, half are available (Beautiful Code and iPhone App Dev: Missing Manual) while two are not (JavaScript: Definitive Guide and Hackers). I wonder if it

I bought 4, half are available (Beautiful Code and iPhone App Dev: Missing Manual) while two are not (JavaScript: Definitive Guide and Hackers). I wonder if it is related to the books themselves (perhaps each are on specific servers) or if it is only a coincidence that our available books match up.