http://book.klll.cc/ebooks/subject/25538.opds 2025-11-16T13:02:42Z Books about United States. Army -- Communication systems Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-11-16T13:02:42Z https://book.klll.cc/ebooks/43515.opds Visual Signaling United States. Army. Signal Corps