Appendix E — Sources

Every figure in this book was verified against a primary source in August 2026. Platform behaviour, market share and regulation in this field move faster than publishing does, so check the date on anything that matters to a decision.

Research

Aggarwal, Murahari, Rajpurohit, Kalyan, Narasimhan and Deshpande. “GEO: Generative Engine Optimization.” ACM SIGKDD 2024. https://arxiv.org/abs/2311.09735

Puerto, Gubri, Green, Oh and Yun. “C-SEO Bench: Does Conversational SEO Work?” NeurIPS 2025, Datasets and Benchmarks Track. https://arxiv.org/abs/2506.11097

Vishwakarma, Kumar and Jamidar. “What Gets Cited: Competitive GEO in AI Answer Engines.” SIGIR 2026. https://arxiv.org/html/2605.25517v1

Xu, Iqbal and Montgomery, Washington University in St. Louis. “Measuring Google AI Overviews: Activation, Source Quality, Claim Fidelity, and Publisher Impact.” May 2026. https://arxiv.org/html/2605.14021

Schulte, Bleeker and Kaufmann, University of St. Gallen. “Don’t Measure Once: Measuring Visibility in AI Search.” April 2026. https://arxiv.org/pdf/2604.07585

Qin et al., Google Research. “Large Language Models are Effective Text Rankers with Pairwise Ranking Prompting.” NAACL 2024. https://aclanthology.org/2024.findings-naacl.97/

Nestaas, Debenedetti and Tramèr, ETH Zürich. “Adversarial Search Engine Optimization for Large Language Models.” https://arxiv.org/html/2406.18382

Bliey and Chatwin. “Answer Engine Optimization: How Agentic AI Reshapes SEO.” Stanford GSBGEN 390, July 2026. SSRN.

Platform documentation

Google Search Central, AI features. https://developers.google.com/search/docs/appearance/ai-features

Google Search Central, common crawlers. https://developers.google.com/search/docs/crawling-indexing/google-common-crawlers

Google Cloud, Vertex AI Search parsing and chunking. https://docs.cloud.google.com/generative-ai-app-builder/docs/parse-chunk-documents

Google Cloud, Check Grounding API. https://docs.cloud.google.com/generative-ai-app-builder/docs/check-grounding

Google Developers Blog, grounding with Google Search. https://developers.googleblog.com/en/gemini-api-and-ai-studio-now-offer-grounding-with-google-search/

Google Developers Blog, Universal Commerce Protocol. https://developers.googleblog.com/under-the-hood-universal-commerce-protocol-ucp/

OpenAI bots and commerce documentation. https://developers.openai.com/api/docs/bots

Anthropic crawler documentation. https://support.claude.com/en/articles/8896518-does-anthropic-crawl-data-from-the-web-and-how-can-site-owners-block-the-crawler

Perplexity crawler documentation. https://docs.perplexity.ai/docs/resources/perplexity-crawlers

Microsoft Learn, chunking documents for retrieval. https://learn.microsoft.com/en-us/azure/search/vector-search-how-to-chunk-documents

Cloudflare, “Content Independence Day: AI options,” July 2026. https://blog.cloudflare.com/content-independence-day-ai-options/

Google patents: generative summaries for search results (US11769017B1), search with stateful chat (US20240289407A1), pairwise ranking prompting (US20250124067A1).

Measurement and industry studies

Pew Research Center, “Google users are less likely to click on links when an AI summary appears,” July 2025. https://www.pewresearch.org/short-reads/2025/07/22/google-users-are-less-likely-to-click-on-links-when-an-ai-summary-appears-in-the-results/

SparkToro, zero-click search analysis, June 2026. https://sparktoro.com/blog/in-2026-less-than-one-third-of-google-searches-still-send-a-click/

Ahrefs, brand visibility correlations. https://ahrefs.com/blog/ai-brand-visibility-correlations

Ahrefs, schema and AI citations. https://ahrefs.com/blog/schema-ai-citations/

Ahrefs, most-cited domains in Gemini. https://ahrefs.com/blog/most-cited-domains-gemini/

Ahrefs, AI traffic volume study. https://ahrefs.com/blog/ai-traffic-increase/

Profound, AI platform citation patterns. https://www.tryprofound.com/blog/ai-platform-citation-patterns

Profound, how ChatGPT sources the web. https://www.tryprofound.com/blog/chatgpt-citation-sources

Semrush, ChatGPT search insights (clickstream). https://www.semrush.com/blog/chatgpt-search-insights/

Semrush and Kevin Indig, the ghost citations study. https://www.semrush.com/blog/the-ghost-citations-study/

Similarweb, AI search statistics 2026. https://aisearch.similarweb.com/blog/gen-ai-stats/

Similarweb, most-cited domains by LLMs. https://www.similarweb.com/blog/marketing/geo/most-cited-domains-llms/

BrightEdge, why AI engines cite different sources but recommend the same brands. https://www.brightedge.com/resources/weekly-ai-search-insights/ai-search-same-brands-different-sources

BrightEdge, YouTube presence in AI search. https://www.brightedge.com/resources/weekly-ai-search-insights/youtube-presence-ai-search

Muck Rack, GenerativePulse. https://media.muckrack.com/static/reports/2025/MuckRack-GenerativePulse2025-1.pdf

Seer Interactive, AI brand visibility and content recency. https://www.seerinteractive.com/insights/study-ai-brand-visibility-and-content-recency

Vercel, the rise of the AI crawler. https://vercel.com/blog/the-rise-of-the-ai-crawler

searchVIU, what AI systems actually see in schema markup. https://www.searchviu.com/en/schema-markup-and-ai-in-2025-what-chatgpt-claude-perplexity-gemini-really-see/

Microsoft Clarity, AI traffic conversion study. https://clarity.microsoft.com/blog/ai-traffic-converts-at-3x-the-rate-of-other-channels-study/

Brave, agentic browser security. https://brave.com/blog/comet-prompt-injection/

John Mueller on llms.txt, Search Engine Roundtable. https://www.seroundtable.com/google-ai-llms-txt-39607.html

Legal and regulatory

FTC, rule on the use of consumer reviews and testimonials. https://www.ftc.gov/business-guidance/resources/consumer-reviews-testimonials-rule-questions-answers

FTC, Operation AI Comply. https://www.ftc.gov/news-events/news/press-releases/2024/09/ftc-announces-crackdown-deceptive-ai-claims-schemes

EU AI Act Article 50 transparency obligations, in force August 2026.

Moffatt v. Air Canada, 2024 BCCRT 149.

Walters v. OpenAI, Georgia, 2025. Starbuck v. Google, filed October 2025.

Regional Court of Munich, case 26 O 869/26, May 2026.

Wikipedia:Conflict of interest. https://en.wikipedia.org/wiki/Wikipedia:Conflict_of_interest

Market and budget

McKinsey QuantumBlack, the agentic commerce opportunity. https://www.mckinsey.com/capabilities/quantumblack/our-insights/the-agentic-commerce-opportunity-how-ai-agents-are-ushering-in-a-new-era-for-consumers-and-merchants

Morgan Stanley Research, agentic commerce market impact outlook. https://www.morganstanley.com/insights/articles/agentic-commerce-market-impact-outlook

Gartner, 2026 CMO spend survey. https://www.gartner.com/en/newsroom/press-releases/2026-05-11-gartner-2026-cmo-spend-survey-finds-cmos-allocate-15-point-3-percent-of-marketing-budgets-to-ai-but-only-30-percent-are-ready-to-scale-ai-capabilities

NIQ, CMO outlook 2026. https://nielseniq.com/global/en/insights/report/2025/cmo-outlook-for-2026/

IPA, Binet and Field effectiveness research. https://ipa.co.uk/knowledge/effectiveness-research-analysis/les-binet-peter-field

Wikimedia Foundation, new user trends on Wikipedia. https://diff.wikimedia.org/2025/10/17/new-user-trends-on-wikipedia/