That is true, hope that helps :)
the act that was passed in the 1800's to exclude an entire group is
C. Chinese Exclusion Act
The north launched an offensive against the south that lead to the overwhelming of the south and the fall of Saigon.
While you didn't really provide the "following" as the comment above me states, in general, the advantage of secondary sources of primary ones is that they perhaps provide a more objective or even just a broader view on a certain topic. While a primary source of the American civil war would be a letter written by a soldier, a secondary source would be a book that describes more letters taken together and discusses possible information regarding them.
