Conversation so far:
What day was Isaac Asimov born on?
Isaac Asimov was born in Petrovichi, Smolensk Oblast, Russian SFSR on an unknown date between October 4, 1919 and January 2, 1920.
What is the closest date to Isaac Asimov's birthday?
01/02/1920
What day did Isaac Asimov choose?
Isaac Asimov celebrated his birthday on January 2.
What was Isaac Asimov's mothers name?
Anna Rachel

Question: What is his fathers name
Self-contained rewrite: What is Isaac Asimov's fathers name?