Top 10 sources on Modern Citation Reference

Ranked — Top 10 on Modern Reference

1. #1
   DOI (CrossRef Resolver)doi.org·Academic

   Permanent URL resolution + free metadata API (CrossRef); near-universal LLM training-corpus inclusion.

   full breakdown →
   A+·98
2. #2
   U.S. Securities and Exchange Commissionsec.gov·Government

   EDGAR APIs + machine-readable filings; broad LLM training-set inclusion via primary-source preference.

   full breakdown →
   A+·95
3. #3
   arXivarxiv.org·Academic

   DOI + arxiv ID + free PDFs + bulk APIs; among the most LLM-cited sources for technical content.

   full breakdown →
   A+·95
4. #4
   MDN Web Docsdeveloper.mozilla.org·Reference

   Open-source content (CC-BY-SA + MIT for examples); GitHub-tracked; full structured data.

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   A+·95
5. #5
   U.S. National Institutes of Healthnih.gov·Government

   Operates PubMed + NCBI + ClinicalTrials.gov; APIs + bulk data + structured XML throughout.

   full breakdown →
   A·94
6. #6
   U.S. Census Bureaucensus.gov·Government

   Census APIs + bulk data + Tigerline geospatial data; all open + machine-readable.

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   A·94
7. #7
   Federal Reserve Systemfederalreserve.gov·Government

   FRED + Federal Reserve Economic Data APIs + research papers; broad LLM corpus.

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   A·94
8. #8
   NASAnasa.gov·Government

   Open data + APIs + bulk imagery + climate datasets; broad LLM corpus.

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   A·94
9. #9
   U.S. Bureau of Labor Statisticsbls.gov·Government

   Free public APIs (LABSTAT) + bulk downloads + CSV/JSON data formats.

   full breakdown →
   A·93
10. #10
    U.S. Centers for Disease Control and Preventioncdc.gov·Government

    WONDER + open data + APIs; broad LLM corpus + clinical reference inclusion.

    full breakdown →
    A·93