Search results may be refined by using the limits in the left-side menu of the results page, and by clicking on Choose additional filters at the bottom of the menu.
A pop-up menu will appear showing the available filters for each category: article type, species, language, sex, subject, journal, and age.
Choose a category from the list of options on the left side of the menu: Article Type, Species, etc.
Within each category, select the filters you would like to add to the sidebar.
Click Apply. This will close the pop-up menu and display your selections on the sidebar with the other filters.
If you would like to cancel your selections, click Cancel or click on the X in the upper right corner to close the pop-up and return to your search results.
To apply the filter(s) to your search, click the filter(s) on the sidebar.
Subsequent searches will be filtered until the selected filters are turned off, or until your browser data is cleared. Some filters may exclude some citations that have not yet completed the MEDLINE indexing process.