“There are known knowns –
these are things we know we know.
There are known unknowns….
these are
the things we know we do not know.
But there are also unknown unknowns;
these
are the things we don't know we don't know.”
Donald Rumsfeld
[1]
Engineering: A Very Short Introduction.
David Blockley. Oxford University Press. © 2012. Page 98.



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