diff --git a/guide/english/agile/actual-time-estimation/index.md b/guide/english/agile/actual-time-estimation/index.md
index 6170334a7e..61a05b383e 100644
--- a/guide/english/agile/actual-time-estimation/index.md
+++ b/guide/english/agile/actual-time-estimation/index.md
@@ -39,7 +39,7 @@ Examples:
 
 Or… 
 
-**This task will be complete by January 10th.**
+**This task will be completed by January 10th.**
 
 Or… 
 
@@ -51,3 +51,6 @@ Or…
 
 - [How do you estimate on an Agile project?](http://info.thoughtworks.com/rs/thoughtworks2/images/twebook-perspectives-estimation_1.pdf)
 
+My addition
+-[The Theory of Constraints in Agile](https://www.leadingagile.com/2018/03/the-theory-of-constraints-in-agile/)
+