<p>
The main difference between #3 and #4 is that #3 is more recent; it was published in 2010 while the other was published in '09.</li>
</ol>
<p>Also, you can buy it cheaper from Barnes and Noble’s website, for $8.60: [AP</a> U.S. History Crash Course (REA), Larry Krieger, Book - Barnes & Noble](<a href=“Online Bookstore: Books, NOOK ebooks, Music, Movies & Toys | Barnes & Noble®”>Online Bookstore: Books, NOOK ebooks, Music, Movies & Toys | Barnes & Noble®)</p>