420 History: How April 20 Became Known as 'Weed Day
These stoner dads claim to have invented the 4/20 holiday
The Real Story Behind Why “4/20” Became a Stoner Holiday – Mother Jones
High holiday: 4/20 traces roots to these high school stoners - WHYY
What Is 4/20? A Brief History and How To Celebrate
What Is 4/20? - StayHipp
The origin of 4/20 Weed Day
Why Is Marijuana Called 420?
What is 420? The meaning behind the day and how it started
4/20 reminders: State urges marijuana users to consume safely
The History of 420