diff --git a/Documentation/API.md b/Documentation/API.md
index b66d9ce..374ceb7 100644
--- a/Documentation/API.md
+++ b/Documentation/API.md
@@ -1,5 +1,8 @@
 # `API` — networking for LCEssentials
 
+Part of the reference set: [Extensions.md](Extensions.md) ·
+[SwiftUI.md](SwiftUI.md) · [UIKit.md](UIKit.md).
+
 `API` is an `actor` that wraps `URLSession` for JSON REST calls and multipart
 uploads. One line to send a typed request, decode the response, and get a
 consistent error — instead of re-writing the same `URLRequest` / status-code /