http://www.rssboard.org/rss-specification 720 XTF Search Results (docsPerPage=100;f5-subject=Aerial observation (Military science)) https://catalog.wrhs.org/collections/search?docsPerPage%3D100;f5-subject%3DAerial%20observation%20(Military%20science) Results for your query: docsPerPage=100;f5-subject=Aerial observation (Military science) Thu, 01 Jan 1970 12:00:00 GMT Military observation balloons (captive and free): a complete treatise on their manufacture, equipment, inspection, and handling, with special instructions for the training of a field balloon company. Widmer, Emil Joseph, 1889- https://catalog.wrhs.org/collections/view?docId=marc/skclmarc202890322046876.mrc https://catalog.wrhs.org/collections/view?docId=marc/skclmarc202890322046876.mrc Thu, 01 Jan 1970 12:00:00 GMT