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llms.txt GeneratorReference sites are the clearest named source family
Reference sources account for 1.48% of the current citation corpus.
Reference is the second-largest named source class, behind social, although the unclassified tail is far larger.
The numbers behind it.
- Reference category share
- Partial hand-maintained source classification.
- 1.48%
- Citation appearances
- 80,769,585 appearances in the verified October 14, 2026 snapshot.
- 80.8M
The evidence.
Source
AI Citation Index
| Measure | Result |
|---|---|
| Reference category share Partial hand-maintained source classification. | 1.48% |
| Citation appearances 80,769,585 appearances in the verified October 14, 2026 snapshot. | 80.8M |
Population and method
Built from 80,769,585 citation appearances across 725,777 unique domains in the latest valid snapshot for 1,928 tracked brands, observed from October 3, 2025 to October 14, 2026.
Where the evidence stops
The index is a changing panel of tracked brands and prompts, not a random sample of all AI responses.
Domain share is observational. It does not establish causal influence or reveal the full retrieval set.
The hand-maintained source taxonomy is partial: 88.40% of citation appearances remain in “other”.
Model attribution, response-level citation denominators, geography, raw prompts, and raw responses are not retained in the public aggregate.
What to do with this
Reference remains visible, but the 88.40% unclassified share prevents a complete source-type ranking.
Cite this fact.
Source study: Citation Sources“Reference sources account for 1.48% of the current citation corpus.”
AI Citation Index - Trakkr Research · Reference sites are the clearest named source family
AI Citation Index · Trakkr Research · Updated 14 October 2026