diff --git a/an invitation to applied category theory.md b/an invitation to applied category theory.md
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+# An Invitation to Applied Category Theory
+
+- a [[book]]
+  - [[fong]] [[spivak]]
diff --git a/knowledge graphs.md b/knowledge graphs.md
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+++ b/knowledge graphs.md	
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 - a [[paper]]
   - [[go]] https://arxiv.org/abs/2003.02320
+  - [[hn]] https://news.ycombinator.com/item?id=28953155
+    - [[Fong & Spivak]]’s textbook [[An Invitation to Applied Category Theory]]
   - [[pull]] [[knowledge graph]]