Generate a correct and concise answer for the question based on the words in the context.

Let me give you an example: Context : Isaac Nicola Romero (1916 in Havana, Cuba -- 1997) was a prominent Cuban guitarist and one of the founders of the modern Cuban Guitar School.
Question : What was Isaac Nicola's city of birth?
The answer to this example can be: Havana
Here is why: According to context Issac Nicola's city of birth is Havana. Hence this is a correct output.

OK. solve this:
Context : Stephen Nissenbaum (A.B. Harvard College, 1961; M.A. Columbia University, 1963; Ph.D., University of Wisconsin--Madison, 1968 ), is Professor Emeritus of the History Department, University of Massachusetts at Amherst, specializing in early American history through to the nineteenth century.
Question : Where did Stephen Nissenbaum study or work?
Answer:
Columbia University