# Querying linked data A matched entity is stored as multiple resources connected by a `Linkage`. Use the standard FHIR R4 search interactions to retrieve linked data (see [Searching FHIR resources](searching-fhir-resources.md)). Get all resources linked to a patient Use the `item` search parameter to find the patient's `Linkage`, and `_include=Linkage:item` to return the linked resources in the same bundle: ``` GET /Linkage?item=Patient/patient-A&_include=Linkage:item ``` Get all linkages in the data store Return every `Linkage` along with its linked resources: ``` GET /Linkage?_include=Linkage:item&_count=100 ``` Count the linkages in the data store ``` GET /Linkage?_summary=count ``` Get clinical data across a linked patient To retrieve another resource type (such as `Observation`) for a patient and everyone linked to them, first read the `Linkage` to get the linked patient IDs: ``` GET /Linkage?item=Patient/patient-A&_include=Linkage:item ``` Then search the target resource type across those IDs: ``` GET /Observation?patient=Patient/patient-A,Patient/patient-B,Patient/patient-C ``` ## See also * **Skills for AI coding assistants (optional).** AWS publishes reusable skills for AWS HealthLake. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query healthlake` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).