diff --git a/04-monitoring.md b/04-monitoring.md
index b923093..91b5708 100644
--- a/04-monitoring.md
+++ b/04-monitoring.md
@@ -131,6 +131,12 @@ sys     0m0,019s
 
 System monitoring does not show whether your application is available to users!
 
+## System monitoring tools
+
+![Linux Performance Observability Tools Overview](assets/linux_observability_tools.png)
+
+Source: Gregg, B. (2021) *Linux Performance.* <https://www.brendangregg.com/linuxperf.html>
+
 ## Network monitoring
 
 - Simple Network Management Protocol (SNMP)
diff --git a/assets/linux_observability_tools.png b/assets/linux_observability_tools.png
new file mode 100644
index 0000000..678e61f
Binary files /dev/null and b/assets/linux_observability_tools.png differ