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LinkOut Help [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2006-.

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LinkOut Help [Internet].

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Information for Libraries

Created: ; Last Update: April 13, 2021.

Estimated reading time: 5 minutes

LinkOut provides direct links from PubMed and other NCBI databases to a wide range of information and services beyond the NCBI systems. LinkOut aims to facilitate access to relevant online resources to extend, clarify, and supplement information found in NCBI databases. LinkOut resources include full-text publications, biological databases, consumer health information, research tools, and more (see examples of LinkOut resources).

How LinkOut Works for Libraries

LinkOut allows participating libraries to link directly from PubMed citations to their library’s link resolver where library full text resources and Interlibrary Loan options are available to their users. Libraries icons and links to their link resolver display in all PubMed citations.

LinkOut does not perform any user verification. Once a user clicks on a link for a local link resolver, access depends on pre-existing licensing agreements between the library and the full-text provider(s).

PubMed and OpenURL-based Services

Section contents:

About PubMed & OpenURL based Services

OpenURL is a syntax for packaging metadata and identifiers describing information objects and for pointing to a user-specific appropriate copy of the object. The syntax has been accepted as a NISO standard.

PubMed supports library link resolver software that use OpenURL syntax through Outside Tool. Outside Tool allows libraries to place a link to their link resolver software on all PubMed records. If your library has implemented a link resolver, see the section Evaluate your Link Resolver to see whether it qualifies for Outside Tool.

Activating Library Icons in PubMed

Library icons may be activated in PubMed: through a special URL to access PubMed, by using a shared My NCBI account, or by signing in to My NCBI.

Displaying Library Icons through a special URL to access PubMed

To display Outside Tool icons through a simple link to PubMed, use the following URL:


Replace Outside Tool with the Outside Tool username assigned by NCBI.

Displaying Library Icons using a shared My NCBI account

My NCBI accounts can be configured so that database filter selections, Outside Tool selections, and highlighting selections can be shared by multiple users. Outside Tool icons can be selected in My NCBI and activated using a special URL. To do this, please follow the instructions in the Sharing My NCBI Account Settings section of this manual.

Displaying Library Icons in My NCBI

Outside tool icons can be selected in My NCBI and displayed while the user is signed in to their My NCBI account. See PubMed Preferences – Outside Tool.

To display icons without signing into My NCBI, set up a Sharing My NCBI Account Settings for your patrons.

Localizing PubMed for Your Users

In addition to displaying library icons via Outside Tool in PubMed, there are a variety of ways to customize the PubMed display, allowing users to link directly from PubMed to library services and other resources. This section provides information on:

About Cookies and Special URLs

Many of the features used to create a localized PubMed environment use “special URLs”. When a user enters PubMed through a special URL, a cookie is placed in the workstation that instructs PubMed to set the preferences indicated by the URL. To use special URLs, the workstation must be able to accept cookies.

Cookies will expire after 8 hours of inactivity. At this time, the PubMed options will be reset to the default settings. To reactivate your preferences, the user must enter PubMed through the special URL again. You can set preferences that will not time out on a workstation by signing the workstation in to My NCBI and selecting Keep me signed in.

Sharing My NCBI Account Settings

My NCBI accounts can be configured so that Filter selections, Outside Tool, and highlighting selections can be shared by multiple users.

To share account settings:


Register for a My NCBI account that will be used to share settings with patrons.


Sign in to the account and click NCBI Site Preferences to select the services you want for your library’s My NCBI account. Under PubMed Preferences:


To select Filters, click PubMed Filters and Icons. On the resulting page search select a popular filter or create a custom filter.


To select an Outside Tool, click Outside Tool. On the next page, select the checkbox next to the desired libraries. You may select up to five libraries.


To select highlighting preferences, click the link Highlighting under Common Preferences. Select the radio button next to the desired color and click “Save”


To select which services to share click the links NCBI Site Preferences and click the Shared Settings link under Common Preferences. On the resulting page, click the check boxes next to the services you would like to share. Only the settings for a service where the Share Selection box is checked will be shared.

After selecting the features you want to share, use the following special URL to activate the settings:



Settings activated using a shared My NCBI account URL will time out after 8 hours of inactivity.

Clearing Settings Using a Special URL

To clear LinkOut settings activated using a special URL and return to the default PubMed display, access PubMed using the following URLs:

To clear the Outside Tool icon:


To clear the myncbishare setting:


In the above URLs, there are two underscores ( _ ) preceding reset.


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