USA. Educational Attainment of the Population 25 Years and Over by Age: 1947 to 2003.
<p>Transferred from <span class="plainlinks"><a class="external text" href="https://en.wikipedia.org">en.wikipedia</a></span> to Commons by <a href="//commons.wikimedia.org/wiki/User:Sreejithk2000" title="User:Sreejithk2000">Sreejithk2000</a> using <a href="https://iw.toolforge.org/commonshelper/" class="extiw" title="toollabs:commonshelper/">CommonsHelper</a>.
</p>
U.S. Census Bureau: <a rel="nofollow" class="external text" href="https://www.census.gov%5C/prod/2004pubs/p20-550.pdf">Educational Attainment in the United States: 2003</a>. Archived <a rel="nofollow" class="external text" href="http://www.sociologycentral.com/text/educ/attain.pdf">here</a>, too.