One of the most detailed Dutch atlas maps of Vietnam is this map in De grote wereldatlas of the Dutch geographer and leading cartographer Ferdinand Jan Ormeling sr. (1912-2002). The atlas is published by Wolters, known of the leading school atlas in the Netherlands, the Bosatlas, but was actually a license edition of the German publisher Bertelsmann. Although the atlas was published during the Vietnam War (1955-1975), the de facto separation in North- and South-Vietnam is not (yet) indicated on the map. A characteristic of this international atlas is that place names are in their original language.
F.J. Ormeling, De grote wereldatlas. Groningen : Wolters, [1961] (COLLBN Atlas 740)