diff --git a/oauth2_http/java/com/google/auth/oauth2/S2A.java b/oauth2_http/java/com/google/auth/oauth2/S2A.java
index acd769fad..9d4256a66 100644
--- a/oauth2_http/java/com/google/auth/oauth2/S2A.java
+++ b/oauth2_http/java/com/google/auth/oauth2/S2A.java
@@ -52,7 +52,8 @@
 /**
  * Utilities to fetch the S2A (Secure Session Agent) address from the mTLS configuration.
  *
- * <p>mTLS configuration is queried from the MDS MTLS Autoconfiguration endpoint.
+ * <p>mTLS configuration is queried from the MDS MTLS Autoconfiguration endpoint. See
+ * https://google.aip.dev/auth/4115 for details.
  */
 @ThreadSafe
 public final class S2A {