These days, printed matters are peppered with lot of http links. For example, this book, published in 2004, contains an abundance of them, and more than a half are broken, though easily recoverable via Google. So it seems to be meaningless nowadays to give an exact http reference, better one should describe it verbosely, possibly by keywords, and refer the reader to Google. But Google itself would be replaced with time by New All-American Altavista Live, or whatever, so on the meta-level, so to say, one shouldn't refer to Google, but just suggest to "search on the Internet". But, alas, with time the Internet itself would be replaced by another media, where people would operate 3-dimensional constructions appearing out of the air, or whatever. So, on the meta-meta-level, one should say something like "search in the surrounding world". I wonder whether one should stop here, as such classical treatises as Futurological Congress obviously suggest that our surrounding world could/would/should be replaced by something else, so one should abandon any attempt to give a precise, or imprecise, reference to anything.