Ключевые слова: address, airmail, anniversary, bill, brazzaville, business, card, celebration, communication, concept, congo republic flag, congolese, congolese flag, congratulation, copy space, correspondence, delivery, design, document, email, envelope, exchange, greeting, holding, investment, invitation, letter, letter of happiness, mail, mailing, message, modern, national, national holiday, nationality, notebook, paper, payment, pen, pictogram, post, post office, postage, postcard, registration, republic of the congo, retro postage, symbol,