마이크로도트
Sign in to savethumb|NSA photo of microdots taped inside the label of an envelope. The envelope was sent by Operation Bolívar|German spies in Mexico City to [[Lisbon during World War II, but was intercepted by Allied intelligence.]]
thumb|NSA photo of microdots taped inside the label of an envelope. The envelope was sent by Operation Bolívar|German spies in Mexico City to [[Lisbon during World War II, but was intercepted by Allied intelligence.]]