Digital Object Identifiers (DOIs) are standard persistent identifiers used to uniquely identify scientific papers and other scholarly digital artifacts. No specific citation is needed for this basic institutional fact.
The claim states that scientific papers are uniquely identified using Digital Object Identifiers. This is a foundational, definitional aspect of modern scholarly publishing and academic infrastructure (as supported in passing by papers such as [0], [3], and [7] which discuss DOIs as standard identifiers). Because it is a matter of standard definition and everyday observation within publishing, it is classified as common knowledge requiring no specific citation receipt.