https://www.history.com/topics/westward-expansion/louisiana-purchase
https://www.monticello.org/site/jefferson/louisiana-purchase
https://www.ducksters.com/history/westward_expansion/louisiana_purchase.php
http://www.socialstudiesforkids.com/articles/ushistory/louisianapurchase.htm
https://kids.kiddle.co/Louisiana_Purchase
http://www.american-historama.org/1801-1828-evolution/louisiana-purchase.htm