diff --git a/book/source/adv/certificates.md b/book/source/adv/certificates.md
index 7e8dbb1..7166388 100644
--- a/book/source/adv/certificates.md
+++ b/book/source/adv/certificates.md
@@ -306,7 +306,7 @@ Keyserver designs have adapted to these challenges. For example, the keys.openpg
 Furthermore, KOO, Hockeypuck keyserver software, and Sequoia's `sq` command-line tool have plans to support or already support 1pa3pc, demonstrating the community's proactive stance on enhancing certificate security. See how [KOO supports 1pa3pc](https://gitlab.com/keys.openpgp.org/hagrid/-/commit/39c0e12ac64588220d36bada6497d8396f5915b3), [Hockeypuck's statement on "HIP 1: Regaining control over public key identity with authenticated key management"](https://github.com/hockeypuck/hockeypuck/wiki/HIP-1:-Regaining-control-over-public-key-identity-with-authenticated-key-management) and [Sequoia's support](https://man.archlinux.org/man/sq-key-attest-certifications.1)).
 
 (social-graph-metadata-leak)=
-### 18.7.2. Metadata leak of social graph
+### Metadata leak of social graph
 
 The OpenPGP Web of Trust, built on third-party certifications, allows OpenPGP software to analyze trust relationships by inspecting the certification graph. This graph, along with designated trust anchors — usually the certificate holder's own key or other trusted entities' certificates — helps infer the legitimacy of a target certificate.