You are using the "Entity linking" tool.
This tool allows you to associate database identifiers to documents.

File containing entities to link.
or
try with this set of articles :

Link biological entities with:
Organisms. (Using taxonomy data from NCBI)
Proteins. (Using protein data from UniprotKB)
Omim diseases. (Using disease data from OMIM NCBI)
Ontology. (Enter an OBO file OBO link)
Note : Upload and treatment of file can take some time, depending on the file size and network speed. Max file size = 25MB



Help Box.
Please upload a file containing the list of articles to link with entities.
The file must be formated as follows: 
Pubmed_id	Title	Article
Pubmed_id2	Title2	Article2
...
Each entry must be "tab" separated.
If you want the software to detect automatically highlight pre-tagged entities, they have to be surrounded by specific markup tags:
    	<protein>protein name</protein> for gene products and proteins.
    	<organism>Organism name</organism&> for model organisms.
    	<disease>disease name</disease> for diseases.
	<ontology>ontology tern</ontology> for ontology terms.