I believe the Majumdar's book, if throuoghly read, covers most of the MCQs. And going through the past papers is a must, as you must have known by now. If these are not enough, go through the various websites with a timeline of history of USA, important inventions by Americans, establishment of Major industries, major wars, Names, political affiliations and the number count of American presidents

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"And how can man die better than facing fearful odds, for the ashes of his fathers, and the temples of his Gods?"