diff --git a/content/3.defense-systems/mok_hok_sok.md b/content/3.defense-systems/mok_hok_sok.md
index 00c78a1f0e52e21fcf327a8f0e8b4dd790332488..598ec3b621d52954882501a3d891d4a92ee6eba1 100644
--- a/content/3.defense-systems/mok_hok_sok.md
+++ b/content/3.defense-systems/mok_hok_sok.md
@@ -21,7 +21,7 @@ contributors:
 
 ## Description
 
-The Mok Hok Sok system was discovered as a type 1 toxin-antitoxin system to stabilize plasmid R1 :ref{doi=10.1128/jb.161.1.292-298.1985}. Sok (Suppression of Killing) is an RNA and serves as the antitoxin. Hok (Host killing) is the toxin and Mok (Modulation of killing) is required for the expression of Hok :ref{doi=10.1016/j.mib.2007.03.003, 10.1093/nar/gkl750}.
+The Mok Hok Sok system was discovered as a type 1 toxin-antitoxin system to stabilize plasmid R1 :ref{doi=10.1128/jb.161.1.292-298.1985}. Sok (Suppression of Killing) is an RNA and serves as the antitoxin. Hok (Host killing) is the toxin and Mok (Modulation of killing) is required for the expression of Hok :ref{doi=10.1016/j.mib.2007.03.003,10.1093/nar/gkl750}.
 Hok/sok are not related to the T4 head protein Hoc and Soc.
 This system defends against T4 phages only, as far as we currently know.