Complex sentence: In 1951, Gerschenkron wrote an essay "Economic Backwardness in Historical Perspective", a cornerstone of his career, and of significance to European economic history.
Split into simpler sentences: In 1951, Gerschenkron wrote a highly important essay titled "Economic Backwardness in Historical Perspective". This essay was a cornerstone of Gerschenkron's career and it is of great significance to European economic history.