The Single Citation Matcher is a useful tool when searching for a specific article when some parts of the article's information may be unknown.
The Single Citation Matcher is available via the PubMed homepage below the search bar, under "Find."

A PubMed Unique Identifier (PMID) is assigned to every abstract indexed in PubMed.
You can find the PMID for an article on the Search Results page under each entry.

The PMID can also be found on the article's abstract page under the abstract text.

If you know the PMID for an article, you may search for it using the search box.