Craniopagus twins known sets of twins of all time. In history, Castor and Pollux fought Greek battles alongside other famous war heroes like Herkules and Achilles. The Greeks held these twins in high standing and they were seen not just as warriors but as gods. Although there are cases of conjoined twins dating back to as early as the 10th century, it was not until 1491 that the first case was documented. Apart from that, Sebastian Munster’s "Cosmographia universalis" provides the true first account of craniopagus twins who happened to live for ten years, exceeding many expectations during that time. He describes
There are known knowns management and strategic planning circles. Known unknowns refers to "risks you are aware of, such as cancelled flights..." Unknown unknowns are risks that come from situations that are so unexpected that they would not be considered. "For example, prior to the invention of the personal computer, manufacturers of typewriters probably didn't foresee the risks to their business". Contemporary usage is largely consistent with the earliest known usages. For example, the term was used in evidence given to the British Columbia Royal Commission of Inquiry into Uranium Mining in 1979: The term also appeared in a 1982 "New Yorker" article on