Get the Referral Sources List. 

This is a listing of all of the referral sources. These are possible answers to the question "how did you find out about us". 

Each Referral source item is represented by a TReferral. The collection of Referral source items is represented by a List of TReferral. 

A token is passed for authentication. If the authentication fails, or other errors occur, no referral sources are returned. The result of the authentication is represented by a TAuthenticate object. 

This function has security level "Unrestricted", and can be accessed by any authenticated user.

[WebMethod(Description = "Gets a list of all referral sources")]
public TAuthReferralList GetReferralSources(string token);