https://www.britannica.com/sports/ice-hockey/The-National-Hockey-League 

https://www.history.com/news/who-invented-hockey-origins-canada 

https://www.history.com/news/who-invented-hockey-origins-canada 

https://icehockeycentral.com/the-power-of-evolution-how hockey-has-transformed-over-time/ 

https://www.nhl.com/history/a-brief-history-of-the-league 

https://www.iihf.com/en/statichub/4682/who-we-are