diff --git a/fi1/README.md b/fi1/README.md
index b4efcde..f20cf82 100644
--- a/fi1/README.md
+++ b/fi1/README.md
@@ -140,6 +140,8 @@ Implementation notes:
 
 ![system architecture template](./system_architecture_template.svg)
 
+[Diagram source](https://lucid.app/lucidchart/10340c4d-1a8d-4c98-95cc-b079df613cf9/edit?invitationId=inv_2b28b6cb-aeca-47e4-82bf-102b7a6528fd)
+
 ## Example processes - modeling and notes
 To be able to validate the system template and choose specific components from it let's analyse the processes we know of and see how easy it is to implement them.
 Would be good to draw sequence diagrams to try to understand different processes.