Ключевые слова: aged, albert, america, american, antique, author, background, canceled, card, collect, collectible, collection, color, commemorative, communication, correspondence, einstein, france, germany, heritage, historic, intellectual, letter, mail, mathematician, old, paper, perforated, philatelist, philately, portrait, post, postage, postal, postcard, postmark, retro, scientist, stamp, states, theoretical physicist, united, us, usa, used, vintage,