Schemes including Crotalus horridus

• IUCN Red List of Threatened Species. Version 2012.1 Crotalus horridus
• The Reptile Database (Crotalus_horridus) Crotalus horridus
• IUCN Red List of Threatened Species. Version 2012.2 (64318) Crotalus horridus
• NatureServe Explorer: An online encyclopedia of life. Version 7.1 (ELEMENT_GLOBAL.2.100455) Crotalus horridus
• GBIF (2444468) Crotalus horridus