University of Missouri
Exploring Constitutional Conflicts: Select Hot Constitutional Issues
Among other issues considered, Hot Constitutional Issues probes into the constitutionality of giving Washington, D.C. a vote in the House of Representatives, raised in 2009.
Annenberg Foundation
Annenberg Classroom: Twenty Third Amendment
Text of the 23rd Amendment and accompanying explanation in Annenberg Classroom Civics Education site.
Other
Post Gazette: 23 District of Columbia Suffrage
This resource contains a brief explanation of what the 23rd amendment does and where it originated.
Siteseen
Siteseen: Government and Constitution: 23rd Amendment
Short, simple summary with the full text of the 23rd amendment that gave the people in the District of Columbia the right to vote for President.