Try using a variety of search terms when using the indexes in the encyclopedias and books, broadening the topic when you can't find your particular subject.
Check the index of American Heritage Magazine to the left at the back of the Magazine Room, just before entering the Parkman Room. Many of your topics will have good articles over the years.
Not all the books on the Reserve Cart are noted below. And not all useful books are on the cart. Many remain upstairs, and may be checked out. You may find them by using our electronic catalog or looking in the areas (by Dewey numbers on the spines) where the ones on the cart came from, especially in the 973.5 history section upstairs.
Reference books are located in the Reference section, not on the cart.