> 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/opencitations.md).

# OpenCitations in Duaer

In Duaer: Papers that cite a DOI, or the papers it references, from the open OpenCitations index, newest first, with titles, authors, venue, and self-citation flag. One successful search uses 1 credit.
## What you get

Duaer OpenCitations walks the citation graph of one paper using the open OpenCitations index and adds titles and authors from OpenCitations Meta.

Pick Duaer Data → OpenCitations in the node creator, or open the [data market](/getting-started/data-market.md). Related: [papers](/getting-started/papers.md), [crossref](/getting-started/crossref.md), [icite](/getting-started/icite.md).

## When to use it

- See who cited a paper recently and in which journals.
- List the references of a paper to follow its sources.

## When not to use it

- Searching papers by words. Use [papers](/getting-started/papers.md).
- Complete counts for every paper. Open indexes miss some publishers.

## Search on the canvas

1. Open the node creator and pick Duaer Data → OpenCitations.
2. Fill DOI (such as 10.1038/nature12373). Optional: Direction.
3. Limit defaults to 10, max 20. Execute.

A search uses 1 credit only when it returns rows. No rows, wrong input, or an upstream failure uses 0.

## Call the API

- GET https://api.duaer.com/v1/data/opencitations?doi=10.1038/nature12373&limit=10
- Authorization: Bearer <Duaer key>

The call skill below matches Copy skill in the Duaer data market, with parameters, examples, and result fields.

## Call skill

Same text as Copy skill.

```
---
name: duaer-opencitations
description: >-
  Duaer OpenCitations. Papers that cite a DOI, or the papers it references, from the open OpenCitations index, newest first, with titles, authors, venue, and self-citation flag.
  One successful search uses 1 Duaer credit.
---

# Duaer OpenCitations

Duaer OpenCitations walks the citation graph of one paper using the open OpenCitations index and adds titles and authors from OpenCitations Meta.

## When to use

- See who cited a paper recently and in which journals.
- List the references of a paper to follow its sources.

## When not to use

- Searching papers by words. Use https://skills.duaer.com/papers.md.
- Complete counts for every paper. Open indexes miss some publishers.

## Call

`GET https://api.duaer.com/v1/data/opencitations?doi=10.1038/nature12373&limit=10`

Header: `Authorization: Bearer <Duaer key>`

Use an account key or a model API key.

Get a Duaer key: https://skills.duaer.com/keys.md

## Parameters

Provide `doi`.

- `doi` — DOI of the paper, such as 10.1038/nature12373.
- `direction` — Optional. citations (who cites it) or references (what it cites). Default citations.
- `limit` — Optional. Rows to return, from 1 to 20. Default 10.

## Examples

- `GET https://api.duaer.com/v1/data/opencitations?doi=10.1038/nature12373&limit=10` — the ten newest citing papers.
- `GET https://api.duaer.com/v1/data/opencitations?doi=10.1038/nature12373&direction=references` — what the paper cites.

## Result

The response is `{ "items": [...] }`. Each item has `source`, `title`, `url`, and `summary`, plus:

- `doi` — DOI of the citing or cited paper.
- `direction` — citing or cited, relative to your DOI.
- `authors`, `venue`, `published`, `type` — metadata from OpenCitations Meta.
- `selfCitation` — true when authors or journal overlap.

Fields without a value are left out.

## Credits

A search that returns at least one row uses 1 credit.
An empty search, a search that finds nothing, or a failed search uses 0.
Wrong input returns 400 with a message and uses 0.
No remaining credits returns 402 and does not search.
A missing key returns 401.

## Related

- https://skills.duaer.com/papers.md
- https://skills.duaer.com/crossref.md
- https://skills.duaer.com/icite.md

```
## Questions

### How many credits does a OpenCitations search use in Duaer?

One credit when Duaer returns rows. A search with no rows or an error uses 0.

### Does Duaer OpenCitations cover every citation?

No. It covers open citation data from Crossref and other sources. Some publishers do not share references.

## Related

- [Search papers in Duaer](https://doc.duaer.com/getting-started/papers.md)
- [Search Crossref in Duaer](https://doc.duaer.com/getting-started/crossref.md)
- [Search iCite in Duaer](https://doc.duaer.com/getting-started/icite.md)