Complex sentence: All in all he wrote 23 books, the last of which in the year 2002, when he turned 100 years old, an autobiography and many articles, some of which got published as booklets.
Split into simpler sentences: All in all he wrote 23 books, the last of which in the year 2002, when he turned 100 years old, an autobiography. He also wrote many articles, some of which got published as booklets.