From an article at BusinessWeek on how Amazon copes with the Christmas rush for finding and shipping books — it isn’t via the Dewey Decimal system:
[Amazon's Reno warehouse] is a book browser’s dream, but a librarian’s nightmare: The books in these “pick modules” aren’t stocked Dewey Decimal style. Instead, they’re placed randomly and their location is recorded with a handheld scanner, so pickers with scanners can more easily and efficiently find them later when an order comes in.
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