With large format, many photos, and a few famous authors mixed with relative unknowns, these were offered by mail through subscription programs, and enormous numbers of most volumes were published and sold. This unusual state of affairs in a sense mirrored the contents. While the text of the books tended to be relatively brief, superficial, and uninspired, the pages were packed with a multitude of impressive photos. Occasionally sold as a complete set, most often these are offered individually.
Prices vary considerably.
Here's a checklist of all thirty-nine volumes. Russia Besieged Blumenson, Martin. Liberation Botting, Douglas. Europe Botting, Douglas. The Second Front Collier, Richard.