Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE parking_fines (cmi_cross_ref_id VARCHAR)
TABLE: CREATE TABLE cmi_cross_references (cmi_cross_ref_id VARCHAR)

### Question ###
Which cmi cross reference id is not related to any parking taxes?

### Accurate SQL ###

SELECT cmi_cross_ref_id FROM cmi_cross_references EXCEPT SELECT cmi_cross_ref_id FROM parking_fines