the 56-page document , believed to be the only extensive turing manuscript in existence , was written in 1942 at the government code and cypher school at bletchley park , in buckinghamshire .
the notebook , in which he details his work on the foundations of mathematical notation and computer science , was sold for $ 1,025,000 -lrb- £ 698,000 -rrb- in a fine books & manuscripts sale at bonhams in new york on monday .