> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/getting-started/crossrefs.md).

# Search crossrefs in Duaer

In Duaer, look up UniChem compound cross-references by InChIKey with Duaer Data. One successful search uses 1 credit. This page includes the full English call skill.
## What you get

Crossrefs in the Duaer data market returns UniChem compound ids and links across databases. One successful search uses 1 credit.

Add the node from the [Duaer Data category](/getting-started/duaer-data.md) (Crossrefs), or copy the skill on the [data market](/getting-started/data-market.md). Related: [Compounds](/getting-started/compounds.md).

## Search on the canvas

1. Open the node creator, select Duaer Data, then Crossrefs.
2. Enter an InChIKey (a new node starts with aspirin's key).
3. Limit defaults to 10, max 20. Select Execute step.

A successful search uses 1 credit. Production deliverables land in the [data pool](/getting-started/data-pool.md).

## Call the API

- GET https://api.duaer.com/v1/data/crossrefs?...
- Authorization: Bearer <Duaer key>
- inchikey is required.

For keys, refer to [Authentication for the Duaer public API](/api/authentication.md). Below is the same English call skill as Copy skill.

## Call skill

Same text as Copy skill on the Duaer data market. Keep it English.

```
---
name: duaer-crossrefs
description: >-
  Look up UniChem compound cross-references through Duaer by InChIKey.
  One successful search uses 1 Duaer credit.
---

# Duaer crossrefs

Look up UniChem compound cross-references through Duaer with a Duaer key.

## Call

`GET https://api.duaer.com/v1/data/crossrefs?inchikey=BSYNRYMUTXBXSQ-UHFFFAOYSA-N&limit=10`

Header: `Authorization: Bearer <Duaer key>`

Use an account key or a model API key.

Provide `inchikey`.

- `inchikey` — compound InChIKey (for example aspirin: BSYNRYMUTXBXSQ-UHFFFAOYSA-N).
- `limit` — optional. From 1 to 20. Default 10.

## Result

Each item has `source`, `title`, `url`, `summary`, `database`, `compoundId`, `srcId`, and `inchikey`.
Related compounds: https://skills.duaer.com/compounds.md.
Related metabolites: https://skills.duaer.com/metabolites.md.

## Credits

One successful search uses 1 credit.
An empty search, a failed search, a compound that matches nothing, or no remaining credits uses 0.
No remaining credits returns 402 and does not search.
A missing key returns 401.

```
## Questions

### Where do I get an InChIKey in Duaer?

Use [Compounds](/getting-started/compounds.md) to find an InChIKey, then look up crossrefs here.

## Related

- [Search compounds in Duaer](https://doc.duaer.com/getting-started/compounds.md)
- [Search metabolites in Duaer](https://doc.duaer.com/getting-started/metabolites.md)
- [Search drug labels in Duaer](https://doc.duaer.com/getting-started/drug-labels.md)
- [Use the Duaer data market](https://doc.duaer.com/getting-started/data-market.md)