Citation requirements for data provided within the Wolfram Language vary depending on the primary data source and how the information is accessed.

Entity Calls

1. For a given entity and property, evaluate the following code:

   sourceEntity = EntityValue[ entity, property, "Source"]
   EntityValue[ sourceEntity, EntityProperty["Source", "Citation"]]
   

2. If the preceding code yields sources, use them in your citation.
3. If the preceding code does not yield sources, cite as:
   Wolfram Research, Inc., Wolfram|Alpha Knowledgebase, Champaign, IL (2018).

Data Function Evaluations

1. For a given Wolfram Language data function such as ElementData or FinancialData, look up its sources on the Wolfram Knowledgebase source information page.
2. If sources are listed, use them in your citation.
3. If not, cite as:
   Wolfram Research, Inc., Wolfram|Alpha Knowledgebase, Champaign, IL (2018).

Wolfram|Alpha Calls

1. For a single query, use the following citation, where “<query>” is the string submitted to Wolfram|Alpha with any of the =, ==, Ctrl-=, or Wolfram|Alpha functions:
   Wolfram Alpha LLC, 2018. Wolfram|Alpha. WolframAlpha["<query>", "URL"] (access Feb 24, 2018).
2. When using information from numerous Wolfram|Alpha calls, cite collectively as:
   Wolfram Alpha LLC, 2018. Wolfram|Alpha.