MLA style. Clear details and good formatting. I have some resources pasted here.
The Declaration of Independence: http://www.ushistory.org/declaration/document/
The Constitution of the United States:
https://www.archives.gov/founding-docs/constitution-transcript
Supreme Court Landmarks – http://www.uscourts.gov/about-federal-courts/educational-resources/supreme-court-landmarks
15 Supreme Court Cases that Changed America – https://www.cnn.com/2012/10/10/justice/landmark-scotus-cases/index.html
Executive Orders – The American Presidency Project
NAACP was instrumental in the landmark case of Brown v Board of Education. Visit the web site to find information on the case that led to desegregation.
http://www.naacp.org