Notice: Out of an abundance of caution, all Library of Congress research centers will be closed to the public (including researchers and others with reader identification cards) until further notice, to reduce the risk of transmitting COVID-19 coronavirus. All Library-sponsored public programs are also postponed or cancelled through July 1. Online resources and reference services, such as Ask a Librarian, will continue to be available during this time. For more information, see: www.loc.gov/coronavirus.