> For the complete documentation index, see [llms.txt](https://citemed-io.gitbook.io/citemed.io-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://citemed-io.gitbook.io/citemed.io-documentation/advanced-topics/search-term-syntax-and-errors.md).

# Search Term Syntax and Errors

Because you are able to run the same term on multiple databases, you run the risk of using bad syntax on one database that is still valid on another one. See our guide below to the different databases

#### Intro

This guide will help you build search queries for all the major databases we offer.

#### PubMed

Reference Link: <https://pubmed.ncbi.nlm.nih.gov/help/>

#### PubMed Central

[User-guide reference link](https://www.ncbi.nlm.nih.gov/pmc/about/userguide/#search)

#### Cochrane

[CochraneQRG Search syntax.pdf](https://prod-files-secure.s3.us-west-2.amazonaws.com/403a01b1-682f-4f98-a66d-d38465b55214/315823c5-a525-491c-8205-60cf2e3f387f/CochraneQRG_Search_syntax.pdf)

#### [ClinicalTrials.gov](http://ClinicalTrials.gov)

<https://classic.clinicaltrials.gov/api/gui/ref/syntax#andExpr>

Notes:

* ( ) not permitted on these.
* AND OR NOT statements permitted