SELECT DISTINCT T2.source_system_code FROM customer_master_index AS T1 JOIN cmi_cross_references AS T2 ON T1.master_customer_id  =  T2.master_customer_id WHERE T1.cmi_details  =  'Gottlieb ,  Becker and Wyman'
What are the distinct cross reference source system codes which are related to the master customer details 'Gottlieb, Becker and Wyman'?
[Schema (values) (types)]: | local_govt_mdm |  Customer_Master_Index : master_customer_id (text) , cmi_details (number) | CMI_Cross_References : cmi_cross_ref_id (text) , master_customer_id (number) , source_system_code (text) | Council_Tax : council_tax_id (text) , cmi_cross_ref_id (number) | Business_Rates : business_rates_id (text) , cmi_cross_ref_id (number) | Benefits_Overpayments : council_tax_id (text) , cmi_cross_ref_id (number) | Parking_Fines : council_tax_id (text) , cmi_cross_ref_id (number) | Rent_Arrears : council_tax_id (text) , cmi_cross_ref_id (number) | Electoral_Register : electoral_register_id (text) , cmi_cross_ref_id (number);