diff --git a/properties/P000168.md b/properties/P000168.md
index d92f7858d..bb5aaff4d 100644
--- a/properties/P000168.md
+++ b/properties/P000168.md
@@ -4,10 +4,9 @@ name: Countable sets are discrete
 aliases:
 - Countable sets are closed
 - Cid
-- $\omega$C
 refs:
-- mathse: 4995501
-  name: Answer to "Does every door space with an infinite compact set have a single non-isolated point?"
+- mathse: 5150079
+  name: Answer to "Limit points of finite sets"
 - zb: "0665.54003"
   name: On spaces whose denumerable subspaces are discrete (Ganster, Reilly, Vamanamurthy)
 - mathse: 4751818
@@ -18,7 +17,7 @@ Every {P57} subspace of $X$ is {P52}.
 
 Equivalently, every {P57} subset of $X$ is closed.
 
-(For the equivalence, see comments on {{mathse:4995501}}).
+(For the equivalence, see Corollary 2 in {{mathse:5150079}}).
 
 Defined as "cid" in {{zb:0665.54003}} (pg. 283 of 
 [https://gdz.sub.uni-goettingen.de/id/PPN311571026_0039](https://gdz.sub.uni-goettingen.de/id/PPN311571026_0039?tify=%7B%22pages%22%3A%5B299%5D%2C%22view%22%3A%22%22%7D))