A CSF Informative Reference within the CSF Core provides a citation to a related activity from another standard or guideline that can help an organization achieve the outcome described in a CSF Subcategory12.
For example, the Informative Reference for ID.AM-1 (Physical devices and systems within the organization are inventoried) is COBIT 5 APO01.01, which states "Maintain an inventory of IT assets"3.
References: 1: Informative References: What are they, and how are they used? | NIST 2: Everything to Know About NIST CSF Informative References | Axio 3: NIST Cybersecurity Framework v1.1 - CSF Tools - Identity Digital