The locations that I mention on my website were taken from a map we used while flying in the 1960 - 1970s period from Fort Wolters. The map was referred to as the "Crash Rescue Map" and was published by the Army Map Service (which was I believe was part of the Corps of Engineers) at a scale of 1:100,000. Normally the tactical maps we used in Vietnam and the rest of the world were at a 1:25,000 scale and compiled from photogrammetric methods. In the example of the An Khe Stagefield (NM977350) the NM was the 100,000 meter square where the geographic point lay. The 97 was the vertical grid line (longitude) and the 35 was the horizontal grid line (latitude). To find coordinates we would always start reading the map from the lower left corner and then read to the right (longitude) and then upwards (latitude). For those that are interested, there are free converter programs available on the web that convert the coordinates from the those on the Crash Rescue Map to standard coordinates that you could use in your GPS. Or, if you click on the link to the Crash Rescue Map Gallery it will display a larger scale image of the the map and you could correlate these with Bing, Google or other maps. I highlighted the Heliports, Stagefields, etc. for easier location - most are on East -03; East - 05; West - 04; and West - 06.
The Coordinates are the standard latitude/longitude method of finding geographic locations. Jesse Faris has kindly converted all of the Army Map Service coordinates of the Stagefields to their corresponding latitude/longitude coordinates, which I have hyperlinked directly to Google Maps. Thank you Jesse for your hard work!!