Lexicographers routinely source word attestations using historical corpora, quotation files, and citation slips, making this well-established lexicographical practice common knowledge requiring no citation.
The claim describes standard lexicographical methodology (how dictionaries like the Oxford English Dictionary source attestations). None of the retrieved papers specifically examine or test how lexicographers source word attestations, so no source papers are placed. Because the statement is a foundational, factual observation about the practice of lexicography, it is classified as common knowledge under Step 0.