# GEO & AI Search Research: Primary Sources Bibliography

> Source: Show Up On AI · https://showuponai.com/research
> Updated: April 2026

Every claim on this site traces back to a primary source. This page consolidates them.

## Foundational research

- **GEO: Generative Engine Optimization** — Aggarwal et al., Princeton University (2023). https://arxiv.org/abs/2311.09735 — The paper that formalized the term GEO and demonstrated specific techniques can improve generative engine visibility by up to 40%. Source for the +33.9% statistics-citation lift and +41% quotation-citation lift.
- **Search Generative Experience announcement** — Google (2023). Original announcement of what became AI Overviews.

## Market sizing & adoption

- **Gartner** (2024–2026) — Source for the 25% projected decline in traditional search by end of 2026 and the 50% generative-search projection by 2028.
- **Statista** (2026) — Source for the 883M monthly active user figure for ChatGPT.
- **StatCounter Global Stats** (2026) — Source for Google's 89-90% search market share figure.

## Citation patterns & platform behavior

- **ChatGPT citation analyses** (Search Engine Land, Profound, Otterly.AI, 2024–2026) — Independent analyses converging on ~87% of ChatGPT citations corresponding to Bing top results.
- **Perplexity citation source mix** (various analytics studies, 2024–2026) — Source for Reddit accounting for ~6.6% of Perplexity citations.
- **Google AI Overview citation studies** (BrightEdge, Authoritas, Profound, 2024–2026) — Sources for 99% AIO citations from organic top-10, 23% from YouTube, 18% from Wikipedia.

## Conversion & user behavior

- **First Page Sage, Semrush, Bain** (2025–2026) — Sources for the 14.2% AI search conversion rate vs 2.8% organic baseline.
- **SparkToro, Similarweb** (2024–2026) — Sources for 60% overall zero-click rate and 93% Google AI Mode zero-click rate.

## Standards & specifications

- **llms.txt proposal** — Answer.AI / llmstxt.org (2024). https://llmstxt.org/
- **Schema.org vocabulary** — Schema.org consortium. https://schema.org/
- **AI crawler documentation** — Official robots.txt user-agent documentation from OpenAI, Anthropic, Google, Perplexity, Common Crawl, and others.

## Related

- AI Search Statistics: https://showuponai.com/guide/ai-search-statistics
- About Show Up On AI: https://showuponai.com/about