# /nasaads/papers/related

`POST /api/nasaads/papers/related`

Price: 20 credits

Get the papers a NASA ADS record cites, the papers citing it, the review articles citing it, or the papers most often co-read with it, each returned as a full bibliographic record

## How to use it

Walk the citation neighbourhood of one paper. Choose `relation`: references for its bibliography, citations for the works that cite it, reviews for review articles citing it, useful and trending for co-readership rather than citation. An empty list means the record exists but has no neighbours of that kind — an unknown identifier is refused instead. Reference and citation coverage follows what ADS has indexed for the venue, so it is thinner for conference and pre-2000 material than for recent journal articles.

## Parameters

- `access-token` (string, required)

## Request body

- `timeout` (integer) — Max scrapping execution timeout (in seconds) (default: 300; min: 20; max: 1500)
- `paper` (string, required) — ADS bibcode, DOI, arXiv id or abstract URL of the paper whose neighbourhood is returned. All four forms resolve the same record. (examples: "2026AcAau.249..285M", "10.1016/j.actaastro.2026.08.032"; minLength: 1)
- `relation` (string, required) — How the returned papers relate to the one passed in: references are the works it cites, citations the works citing it, reviews the review articles citing it, useful the works most often co-read with it, trending the works currently read by the same readers. (one of: "references", "citations", "reviews", "useful", "trending")
- `count` (integer, required) — Max number of papers to return (min: 1; max: 500)
- `sort` (string) — Field the results are ordered by (default: "relevance"; one of: "relevance", "date", "citation_count", "citation_count_normalized", "read_count", "first_author", "author_count", "indexed_at", "classic_factor", "bibcode")
- `sort_direction` (string) — Order of the sort field (default: "desc"; one of: "asc", "desc")

## Response

### 200 — Successful Response

- `@type` (string) (default: "NasaadsPaper")
- `bibcode` (string, required)
- `url` (string, nullable)
- `abstract` (string, nullable)
- `authors` (array) (default: [])
- `first_author` (string, nullable)
- `author_count` (integer, nullable)
- `affiliations` (array) (default: [])
- `affiliation_ids` (array) (default: [])
- `emails` (array) (default: [])
- `orcids` (array) (default: [])
- `doi` (string, nullable)
- `arxiv_id` (string, nullable)
- `identifiers` (array) (default: [])
- `alternate_bibcodes` (array) (default: [])
- `keywords` (array) (default: [])
- `uat_concepts` (array) (default: [])
- `uat_concept_ids` (array) (default: [])
- `arxiv_categories` (array) (default: [])
- `publication` (string, nullable)
- `publication_raw` (string, nullable)
- `publication_codes` (array) (default: [])
- `publication_note` (string, nullable)
- `publisher` (string, nullable)
- `volume` (string, nullable)
- `issue` (string, nullable)
- `page` (string, nullable)
- `page_range` (string, nullable)
- `page_count` (integer, nullable)
- `electronic_id` (string, nullable)
- `issns` (array) (default: [])
- `isbns` (array) (default: [])
- `published_date` (string, nullable)
- `published_at` (string, nullable)
- `year` (integer, nullable)
- `doctype` (string, nullable)
- `databases` (array) (default: [])
- `record_flags` (array) (default: [])
- `esources` (array) (default: [])
- `data_sources` (array) (default: [])
- `bibgroups` (array) (default: [])
- `grants` (array) (default: [])
- `comments` (array) (default: [])
- `copyright` (string, nullable)
- `citation_count` (integer, nullable)
- `citation_count_normalized` (number, nullable)
- `reference_count` (integer, nullable)
- `read_count` (integer, nullable)
- `indexed_at` (string, 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

No NASA ADS record matches that identifier

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.