http://book.klll.cc/ebooks/subject/39592.opds 2025-08-15T07:16:15Z Books about Military reconnaissance (sorted by popularity) Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-08-15T07:16:15Z https://book.klll.cc/ebooks/71934.opds Balloon observation, and instructions on the subject of work in the basket United States. War Department. Division of Military Aeronautics