The history of 911 how it started and how it's changed over time.

https://www.nena.org/page/911overviewfacts#:~:text=In%20November%201967%2C%20the%20FCC,code%20throughout%20the%20United%20States.

https://www.nena.org/page/911GeneralInfo

https://www.insideedition.com/how-the-death-of-kitty-genovese-birthed-911-and-neighborhood-watches-58288

https://en.wikipedia.org/wiki/Party_line_(telephony)

https://www.britannica.com/topic/bystander-effect#:~:text=bystander%20effect%2C%20the%20inhibiting%20influence,he%20or%20she%20is%20alone