Aydelotte, Jayson D.; Mardock, Alexandra L.; Teixeira, Pedro G.; Brown, Lawrence H. (1 November 2018). «Re-examining the Association Between '4/20' and Fatal Crashes—Doobie-ous Data?». JAMA Internal Medicine178 (11): 1565. doi:10.1001/jamainternmed.2018.5856. PMID30398555.
Staples, John A.; Redelmeier, Donald A. (1 March 2019). «Association Between April 20 Cannabis Celebration and Fatal Crashes». JAMA Internal Medicine179 (3): 456. doi:10.1001/jamainternmed.2018.8094. PMID30715145.
«Bill Actions for HB 1420». nd.gov official portal for North Dakota government. North Dakota legislative branch. Αρχειοθετήθηκε από το πρωτότυπο στις 26 Μαρτίου 2021. Ανακτήθηκε στις 20 Απριλίου 2021.
Aydelotte, Jayson D.; Mardock, Alexandra L.; Teixeira, Pedro G.; Brown, Lawrence H. (1 November 2018). «Re-examining the Association Between '4/20' and Fatal Crashes—Doobie-ous Data?». JAMA Internal Medicine178 (11): 1565. doi:10.1001/jamainternmed.2018.5856. PMID30398555.
Staples, John A.; Redelmeier, Donald A. (1 March 2019). «Association Between April 20 Cannabis Celebration and Fatal Crashes». JAMA Internal Medicine179 (3): 456. doi:10.1001/jamainternmed.2018.8094. PMID30715145.
McKinley, Jesse (April 19, 2009). «Marijuana Advocates Point to Signs of Change». The New York Times. Αρχειοθετήθηκε από το πρωτότυπο στις December 18, 2010. https://web.archive.org/web/20101218011241/http://www.nytimes.com/2009/04/20/us/20marijuana.html. Ανακτήθηκε στις January 23, 2011. «Mr. Hager said the significance of April 20 dates to a ritual begun in the early 1970s in which a group of Northern California teenagers smoked cannabis every day at 4:20 pm. Word of the ritual spread and expanded to a yearly event in various places. Soon, cannabis aficionados were using "420" as a code for smoking and using it as a sign-off on flyers for concerts where the drug would be plentiful. In recent years, the April 20 events have become so widespread that several colleges have discouraged students from participating.»
McKinley, Jesse (April 19, 2009). «Marijuana Advocates Point to Signs of Change». The New York Times. Αρχειοθετήθηκε από το πρωτότυπο στις December 18, 2010. https://web.archive.org/web/20101218011241/http://www.nytimes.com/2009/04/20/us/20marijuana.html. Ανακτήθηκε στις January 23, 2011. «Mr. Hager said the significance of April 20 dates to a ritual begun in the early 1970s in which a group of Northern California teenagers smoked cannabis every day at 4:20 pm. Word of the ritual spread and expanded to a yearly event in various places. Soon, cannabis aficionados were using "420" as a code for smoking and using it as a sign-off on flyers for concerts where the drug would be plentiful. In recent years, the April 20 events have become so widespread that several colleges have discouraged students from participating.»
«Bill Actions for HB 1420». nd.gov official portal for North Dakota government. North Dakota legislative branch. Αρχειοθετήθηκε από το πρωτότυπο στις 26 Μαρτίου 2021. Ανακτήθηκε στις 20 Απριλίου 2021.
