diff --git a/diagrams/core.puml b/diagrams/core.puml
index 2be97d2..2097a07 100644
--- a/diagrams/core.puml
+++ b/diagrams/core.puml
@@ -779,7 +779,11 @@
 !endsub
 
 !startsub Expertise_and_Time_and_Effort
-	"Agent" <-- "0..*" "Expertise_and_Time_and_Effort" : of <
+	"Agent" "by agent 1" <--> "0..*" "Expertise_and_Time_and_Effort"
+!endsub
+
+!startsub Expertise_and_Time_and_Effort
+	"Expertise_and_Skills" "uses expertise and skills 0..*" <--> "0..*" "Expertise_and_Time_and_Effort"
 !endsub
 
 !startsub Position
diff --git a/entities/Expertise_and_Skills.md b/entities/Expertise_and_Skills.md
index 3b3b08b..5990f96 100644
--- a/entities/Expertise_and_Skills.md
+++ b/entities/Expertise_and_Skills.md
@@ -18,6 +18,8 @@ description: [Multilingual String](../datatypes/Multilingual_String.md)
 
 <a name="rel__is-possessed-through">is-possessed-through</a> / [possesses](../entities/Expertise_and_Skills_Possession.md#user-content-rel__possesses) : A Expertise and Skills can be possessed in any number of [Expertise and Skills Possessions](../entities/Expertise_and_Skills_Possession.md).
 
+<a name="rel__is-used-as-a-resource">is-used-as-a-resource</a> / [uses-expertise-and-skills](../entities/Expertise_and_Time_and_Effort.md#user-content-rel__uses-expertise-and-skills) : A Expertise and Skills can be used as a resource in any number of [Expertise and Time and Effort](../entities/Expertise_and_Time_and_Effort.md).
+
 ---
 ## References
 <a name="fn1">\[1\]</a> Source: The Cambridge Dictionary of English. https://dictionary.cambridge.org/dictionary/english/expertise
diff --git a/entities/Expertise_and_Time_and_Effort.md b/entities/Expertise_and_Time_and_Effort.md
index be07229..9895498 100644
--- a/entities/Expertise_and_Time_and_Effort.md
+++ b/entities/Expertise_and_Time_and_Effort.md
@@ -24,6 +24,9 @@ Besides those of [Resource](../entities/Resource.md):
 
 <a name="rel__by-agent">by-agent</a> / [is-agent-in2](../entities/Agent.md#user-content-rel__is-agent-in2) : An Expertise and Time and Effort references the [Agent](../entities/Agent.md) whose expertise, time and effort it would be.
 
+<a name="rel__uses-expertise-and-skills">uses-expertise-and-skills</a> / [is-used-as-a-resource](../entities/Expertise-and-Skills.md#user-content-rel__is-used-as-a-resource) : An Expertise and Time and Effort references any number of [Expertises and Skills](../entities/Expertise_and_Skills.md) belonging to the Agent who is providing its expertise and time.
+
+
 ---
 ## References
 <a name="fn1">\[1\]</a> Source: The Cambridge Dictionary of English. https://dictionary.cambridge.org/dictionary/english/expertise