Map of the <a href="https://en.wikipedia.org/wiki/Battle_of_Chosin_Reservoir" class="extiw" title="w:Battle of Chosin Reservoir">Battle of the Changjin (Chosin) Reservoir</a>.
United States Army
<a rel="nofollow" class="external free" href="http://www.history.army.mil/brochures/kw-chinter/chinter.htm">http://www.history.army.mil/brochures/kw-chinter/chinter.htm</a> U.S. Army Center of Military History