Question

(corroboration)How long does this document either support or expand the textbook version of the montgomery bus boycott?

Answer 1

Answer:

It doesn´t, taken in account the word long.

Explanation:

It seems to me that the question should be formulated like this:

How does this document etc.

Because the either supporting or expanding of the textbook version can´t be measured in time; you either support it or you expand on it.