Vietnam, Laos, and Cambodia, Joint Operations Graphic 1:250,000
<a href="https://en.wikipedia.org/wiki/Defense_Mapping_Agency" class="extiw" title="w:Defense Mapping Agency">Defense Mapping Agency</a>
Courtesy of the <a rel="nofollow" class="external text" href="http://legacy.lib.utexas.edu/maps/jog/vietnam/">University of Texas Libraries, The University of Texas at Austin</a>; also <a href="https://en.wikipedia.org/wiki/United_States_Geological_Survey" class="extiw" title="w:United States Geological Survey">United States Geological Survey</a> (<a rel="nofollow" class="external autonumber" href="https://store.usgs.gov/assets/MOD/StoreFiles/NGA/1501ANF4702_geo.pdf">[1]</a>)