diff --git a/properties/P000139.md b/properties/P000139.md
index decdcdd94..1fe0a4d06 100644
--- a/properties/P000139.md
+++ b/properties/P000139.md
@@ -1,8 +1,20 @@
 ---
 uid: P000139
 name: Has an isolated point
+aliases:
+- Not crowded
+- Not dense-in-itself
+refs:
+- mathse: 3823020
+  name: "Reference request: crowded space"
+- wikipedia: Dense-in-itself
+  name: "Dense-in-itself on Wikipedia"
 ---
 
 Some singleton $\{x\}\subseteq X$ is an open set.
 
-Compare with {P107}.
\ No newline at end of file
+*Note*: A space that fails to satisfy {P139}, 
+i.e., a space without any isolated points, is called "dense-in-itself" or "crowded". 
+See {{wikipedia:Dense-in-itself}} and {{mathse:3823020}}.
+
+Compare with {P107}.