Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE parking_fines (cmi_cross_ref_id VARCHAR); CREATE TABLE cmi_cross_references (cmi_cross_ref_id VARCHAR)
### Question:
Which cmi cross reference id is not related to any parking taxes?
### Answer:
SELECT cmi_cross_ref_id FROM cmi_cross_references EXCEPT SELECT cmi_cross_ref_id FROM parking_fines