diff --git a/spacetime_penrose_area_charge_v2.txt b/spacetime_penrose_area_charge_v2.txt
index 571ad7b..635d860 100644
--- a/spacetime_penrose_area_charge_v2.txt
+++ b/spacetime_penrose_area_charge_v2.txt
@@ -147,6 +147,7 @@ contributions end and the classical machinery begins.
   complete connected asymptotically flat three-manifold with $R_h\ge 0$
   satisfies $E_h\ge |P_h|_\delta$, with equality if and only if
   $(N,h)$ is Euclidean.
+./schoen-yau-1979.pdf ./witten-1981.pdf
 
 (T3) Static vacuum uniqueness (Bunting--Masood-ul-Alam 1987).
   A complete three-dimensional static vacuum data set $(N,h,N)$ with