diff --git a/entries/sigint.txt b/entries/sigint.txt
index 0bd1cec..613b9da 100644
--- a/entries/sigint.txt
+++ b/entries/sigint.txt
@@ -2,5 +2,6 @@ SIGINT
 
 Abbrev. Signals Intelligence. Data obtained via espionage or from
 public sources which is used by the secret police of a nation state.
-Hardware or software systems which contain backdoors to facilitate
-covert data collection are described as being "SIGINT enabled".
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+Hardware or software systems which contain back doors to facilitate
+covert data collection are described as being "SIGINT enabled".
+Also see back door.
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