# /opencitations/works/references

`POST /api/opencitations/works/references`

Price: 5 credits

List the works one work cites. Each result is a single citation link with its own OpenCitations identifier, the identifiers of the citing and cited work, the date the citing work appeared, the interval between the two publications, and whether the pair is a journal or author self-citation

## How to use it

This is the reference list as OpenCitations reconstructed it from what publishers deposited, so it covers only cited works that are themselves in the index and is smaller than the bibliography printed in the paper. An empty result therefore means nothing was deposited, not that the paper cites nothing. Every `cited` bundle here resolves through /opencitations/works. When you take fewer rows than the work has references, pass `sort_by`: the default order is the index's own and repeating the call is not a way to get the same slice back.

## Parameters

- `access-token` (string, required)

## Request body

- `timeout` (integer) — Max scrapping execution timeout (in seconds) (default: 300; min: 20; max: 1500)
- `created_in` (string, nullable) — Keep only edges whose creation date starts with this text, so `2020` takes a whole year and `2020-03` one month (examples: "2020", "2020-03"; minLength: 1)
- `is_journal_self_citation` (boolean, nullable) — Keep only edges where the citing and cited work appeared in the same journal, or only those where they did not
- `is_author_self_citation` (boolean, nullable) — Keep only edges where the citing and cited work share at least one author, or only those where they share none
- `require` (array, nullable) — Drop edges that state no value for these fields (one of: "creation", "timespan")
- `sort_by` (string, nullable) — Field to order the edges by (one of: "creation", "timespan", "oci")
- `sort_order` (string, nullable) — Order direction, ascending unless stated (one of: "asc", "desc")
- `id` (string, required) — Identifier of the citing work: a DOI, PubMed id, OpenAlex id or OpenCitations Meta id, written with its prefix. A plain DOI or a doi.org address is accepted too (examples: "doi:10.1038/nature12373", "pmid:23903748", "omid:br/06120344846", "openalex:W2159974629"; minLength: 1)
- `count` (integer, required) — Number of references to return (examples: 100; min: 1)

## Response

### 200 — Successful Response

- `@type` (string) (default: "OpenCitationsCitation")
- `oci` (string, required)
- `citing` (object, nullable)
  - `@type` (string) (default: "OpenCitationsWorkRef")
  - `omid` (string, nullable)
  - `doi` (string, nullable)
  - `pmid` (string, nullable)
  - `pmcid` (string, nullable)
  - `openalex` (string, nullable)
  - `other_ids` (array) (default: [])
- `cited` (object, nullable)
  - `@type` (string) (default: "OpenCitationsWorkRef")
  - `omid` (string, nullable)
  - `doi` (string, nullable)
  - `pmid` (string, nullable)
  - `pmcid` (string, nullable)
  - `openalex` (string, nullable)
  - `other_ids` (array) (default: [])
- `creation_date` (string, nullable)
- `timespan` (string, nullable)
- `is_journal_self_citation` (boolean, nullable)
- `is_author_self_citation` (boolean, nullable)

## Errors

### 422 — Validation Error

The request body did not validate

What to do: Check the fields against this schema. A URN with the wrong prefix is the most common cause.

- `detail` (array)
  - `loc` (array, required)
  - `msg` (string, required)
  - `type` (string, required)
  - `input` (any)
  - `ctx` (object)

### 408

The request ran past its time limit

What to do: Raise `timeout` in the request body, up to the maximum this endpoint documents. Lowering `count` or turning off the `with_*` flags also helps, because less work finishes sooner.

### 412

The entity was not found, or a precondition failed

What to do: Retrying will not help: either the entity does not exist, or the input points at a different one.

### 429

Too many requests: a rate limit or a usage window is exhausted

What to do: When the response carries an X-Retry-After header, wait that many seconds and retry: the same number is in the body as `detail.retry_after`, and the limit clears once that window passes. The message in the body names the limit that was hit.

### 500

Something broke on our side

What to do: Retrying will not help. If it keeps happening, send us the X-Request-ID from the response headers.

### 529

Rate limit reached, or the endpoint is overloaded

What to do: Wait at least 30 seconds, then retry.

## Response envelope

Success: Array of objects (may be empty if no results)

Error: Error may coexist with partial results if it occurs mid-execution. Check X-Error header and status code.

Every response carries these headers:

- `X-Error` — Error message text (present only on error)
- `X-Request-ID` — Unique request identifier
- `X-Execution-Time` — Execution time in seconds
- `X-Result-Count` — How many records the body carries. 0 means an empty result, which is a normal answer and not by itself an error. A non-zero count can come back together with X-Error when the failure happened partway through — read this header and X-Error independently.
- `X-Total-Available-Results` — How many records exist for this query, when the endpoint can say. On a `dry_run` request this is the answer and the body is empty. It saturates: the endpoint's documented maximum means 'at least that many', any smaller number is exact.
- `X-Warning` — Present when the request body carried keys this endpoint does not document. They were ignored, so any filter you meant to apply through them did not apply. Check the spelling against this schema and retry.
- `X-Retry-After` — Seconds to wait before retrying. Present only on 429.