Ключевые слова: appearing, black, blank, bulletin, business, classified, concept, confidential, cork, correspondence, cover, covert, cut, document, envelope, espionage, file, folder, government, information, ink, letter, list, military, mission, mystery, national, office, old, open, paper, phrase, restrictions, retro, secrecy, secret, sign, supplies, symbol, text, top, torn, vintage, white, word,