“…Second, we introduce three types of referrals: (1) customer-to-potential customer referrals, where the referrer is a customer of the supplier firm, for example, an iPhone user recommends to his friend to purchase an iPhone (Arndt, 1967); (2) horizontal referrals, where the referrer is not a customer of the supplier firm, for example, a contract lawyer refers her client to a lawyer who specializes in personal injury (Spurr, 1988); and (3) supplierinitiated referrals, where the supplier firm matches the referrer and a potential customer, as when SAS requests the U.S. Treasury Department to refer SAS to other government departments (Lee, 2008).…”