CREATE TABLE business_rates (business_rates_id NUMBER, cmi_cross_ref_id NUMBER)
CREATE TABLE council_tax (council_tax_id NUMBER, cmi_cross_ref_id NUMBER)
CREATE TABLE parking_fines (council_tax_id NUMBER, cmi_cross_ref_id NUMBER)
CREATE TABLE cmi_cross_references (cmi_cross_ref_id NUMBER, master_customer_id NUMBER, source_system_code CLOB)
CREATE TABLE benefits_overpayments (council_tax_id NUMBER, cmi_cross_ref_id NUMBER)
CREATE TABLE rent_arrears (council_tax_id NUMBER, cmi_cross_ref_id NUMBER)
CREATE TABLE customer_master_index (master_customer_id NUMBER, cmi_details CLOB)
CREATE TABLE electoral_register (electoral_register_id NUMBER, cmi_cross_ref_id NUMBER)

What are the distinct cross reference source system codes which are related to the master customer details 'Gottlieb, Becker and Wyman'?
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'
SELECT DISTINCT "T2"."source_system_code" FROM "customer_master_index" "T1" JOIN "cmi_cross_references" "T2" ON "T1"."master_customer_id" = "T2"."master_customer_id" WHERE "T1"."cmi_details" = 'Gottlieb ,  Becker and Wyman'