Complex sentence: After returning from exile on the 22nd of January 1947 he dedicated himself to pharmacy, carried out research and continued to write, although he died without finishing the extended version of his main work, "Mathematics of History".
Split into simpler sentences: After returning from exile on the 22nd of January 1947 he dedicated himself to pharmacy, did research and went on writing. He died without finishing the extended version of his main work, "Mathematics of History".