Explanation:
<em>1</em><em>.</em><em> </em><em>Listin</em><em>g</em><em> </em><em>books</em>
<em>2</em><em>.</em><em> </em><em>Lis</em><em>ting</em><em> </em><em>maga</em><em>zines</em><em> </em><em>or</em><em> </em><em>journ</em><em>al</em><em> </em><em>ar</em><em>ticle</em>
<em>3</em><em>.</em><em> </em><em>Lis</em><em>ting</em><em> </em><em>web</em><em>site</em>
<span>Primary sources are first-hand accounts of a topic while secondary sources are any account of something that is not a primary source. Published research, newspaper articles, and other media are typical secondary sources. Secondary sources can, however, cite both primary sources and secondary sources.
</span><span> Hope this helps :) :)</span>
The way that camels help increase trade across geographic barriers of northern Africa is : Camels helped with transportation.
Back
then, we still have not developed machine based transportation
vehicles, so we rely on ships and carts. Since the horses are unable to
cross pass the desert, most of the animals that is used on northern
Africa trade were camels.
