- https://rondreis.nl/rondreis-verenigde-staten/informatie/bezienswaardigheden
- https://www.nps.gov/stli/index.htm
- https://kids.nationalgeographic.com/history/article/statue-of-liberty
- https://www.goldengate.org/exhibits/facts-and-figures-about-the-bridge
-http://www.bridgerail.net/golden-gate-bridge-suicides/demographics
- https://architectuul.com/architecture/empire-state-building
- https://www.nps.gov/moru/learn/historyculture/index.htm
- https://www.history.com/topics/landmarks/grand-canyon
- https://niagarafalls.ca/living/about-niagara-falls/facts.aspx ?????
- https://www.orlando-florida.net/50-things-you-didnt-know-about-disney-world/