context: NARA also maintains the Presidential Library system, a nationwide network of libraries for preserving and making available the documents of U.S. presidents since Herbert Hoover. The Presidential Libraries include:
question: అమెరికా అధ్యక్షుడి డాక్యుమెంట్లను భద్రపరిచే వ్యవస్థ ఏమిటి?
answers: Presidential Library system