1. 2013. Amazon.com Inc. Amazon prime air. http://www.amazon.com/primeair. 2013. Amazon.com Inc. Amazon prime air. http://www.amazon.com/primeair.
2. 2014. DHL International GmbH. DHL parcelcopter launches initial operations for research purposes. http://www.dhl.com/en/press/releases/releases_2014/group/dhl_parcelcopter_launches_initial_operations_for_research_purposes.html. 2014. DHL International GmbH. DHL parcelcopter launches initial operations for research purposes. http://www.dhl.com/en/press/releases/releases_2014/group/dhl_parcelcopter_launches_initial_operations_for_research_purposes.html.
3. 2015. Leo Kelion. Alibaba begins drone delivery trials in China. http://www.bbc.com/news/technology-31129804. 2015. Leo Kelion. Alibaba begins drone delivery trials in China. http://www.bbc.com/news/technology-31129804.
4. 2016. Andrew Liptak. 7-Eleven just made the first commercial delivery by drone. http://www.theverge.com/2016/7/23/12262468/7-11-first-retailer-deliver-food-drone.. 2016. Andrew Liptak. 7-Eleven just made the first commercial delivery by drone. http://www.theverge.com/2016/7/23/12262468/7-11-first-retailer-deliver-food-drone..
5. 2016. Rodrique Ngowi. UPS testing drones for use in its package delivery system. http://phys.org/news/2016-09-ups-drones-package-delivery.html. 2016. Rodrique Ngowi. UPS testing drones for use in its package delivery system. http://phys.org/news/2016-09-ups-drones-package-delivery.html.