Heh, those horrible ole Death Merchant books I sometimes read can occasionally be educational. Book #51, The Inca File, deals with a mission to prevent Soviet scientists from recovering ancient Incan quipu, knotted strings used to record information, that contained all sorts of supercool Inca medical knowledge and so on. Quipu are real, and it seems some scientists have determined the Incas could actually record words with them, not just numbers. And to think I first heard of them as a teenager by reading a violent pulp novel....