Vendor wording quoted or paraphrased in the lesson, read 13 Nov 2026 (Bangkok time) through firecrawl search results.
These sites sell SEO tools: named in the lesson, never linked.

Ahrefs help center, "What is Parent Topic, and how to use it?" (help.ahrefs.com/en/articles/13040767):
  "To identify the Parent Topic, we take the #1 ranking page for the keyword and find the query responsible for sending the most search traffic to that page."
Keyword Insights blog, "17 Best Keyword Clustering Tools" (keywordinsights.ai/blog/keyword-clustering-tools/):
  "The Keyword Clustering feature in Keyword Insights uses real-time Google SERP data to intelligently group keywords that rank for similar results."
MarketMuse home page (marketmuse.com), search snippet:
  "MarketMuse's patented AI automatically analyzes your entire content inventory, then pinpoints high-value topic clusters"
SemScraper guide, "Keyword Clustering by SERP Similarity" (semscraper.com/en/guides/keyword-clustering-serp), search snippet:
  "3 to 4 in common is the most common threshold."
RankYak topical map generator page, "What comes back":
  "Four to eight articles under each pillar. One specific question each, with the phrase a searcher types."
NEURONwriter keywords grouper page:
  "This is a basic keyword grouping tool based on common text processing algorithms with a very basic method of text distance analysis."

Tools that could not be run (13 Nov 2026, Playwright browser, no account):
- RankTree topical map generator (ranktree.io/topical-map-generator): the "Generate My Topical Map Free" button opened ranktree.io/sign-up.
- seo.ai keyword clustering tool (seo.ai/tools/topic-cluster-tool): after "Generate Topic Clusters", a reCAPTCHA "I'm not a robot" check appeared; not bypassed.
- SemanticRelevance topical map creator (semanticrelevance.com/seo-tools/topical-map-creator/): HTTP 403, page title "Checking your browser before accessing".
