Wiktionary
letterheaded
a. Printed with a letterhead.
Usage examples of "letterheaded".
It contained various toiletries, a pair of espadrilles, some soiled shirts, a dead passport (the young blond face erect with classic vanity), and a travel pouch full of loose matter: credit-card counterfoils, bills, used tickets, a slip of note-paper letterheaded the Cymbeline, Stratford-on-Avon, with a telephone number and appointment time on one side and a message from Selina on the other.
No need for either of them to articulate that this chop on almost any Brock letterheaded document, correctly couched and dated validated it, committing Brock's of Yokohama through him to whatever was on the paper.