National Aeronautics and Space Administration. Lyndon B. Johnson Space Center. 2/17/1973 reference URL: https://dp.la/item/cabbf2f53a9a4d3e58a936c991c5cb6e
National Aeronautics and Space Administration. Lyndon B. Johnson Space Center. 2/17/1973 reference URL: https://dp.la/item/b69fc16eebef725b635ca7f5755d4e17
National Aeronautics and Space Administration. Lyndon B. Johnson Space Center. 2/17/1973 reference URL: https://dp.la/item/b3261527e9bfba07773a21df4c1e5140