Articles: 

Drone Registration: https://www.aopa.org/news-and-media/all-news/2017/november/16/house-votes-to-restore-drone-registration 

Cell Phone Towers: https://www.rt.com/usa/410458-flying-cow-drones-puerto-rico/

Super Drone Train: https://www.theverge.com/2017/8/6/16103626/amazon-patent-network-of-mobile-drone-maintenance-delivery-platforms

Bee Hive: https://www.theverge.com/2017/6/23/15860668/amazon-drone-delivery-patent-city-centers

Amazon Prime Air: https://www.digitaltrends.com/cool-tech/amazon-prime-air-delivery-drones-history-progress/

Drone Registration Numbers: http://fortune.com/2017/01/06/drones-registrations-soaring-faa/