письмо-доверенность – английский перевод

letter of authorization; proxy (a written document that officially gives someone the authority to do something for another person, for example by voting at a meeting for them: "A creditor may give a proxy to any person of full age requiring him or her to vote for or against any specified resolution. "proxy materials/cards/forms. CBED Alexander Demidov); authorization letter (Johnny Bravo)