diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..5ff7fee
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "40 Extras/OOP/die_einen_da"]
+	path = 40 Extras/OOP/die_einen_da
+	url = git@collaborating.tuhh.de:e-24/courses/oop/exo/2026/g08/die_einen_da.git
diff --git a/.obsidian/app.json b/.obsidian/app.json
index 26b1465..c99326f 100644
--- a/.obsidian/app.json
+++ b/.obsidian/app.json
@@ -9,7 +9,5 @@
     "downscalePercent": 100
   },
   "promptDelete": false,
-  "newFileLocation": "folder",
-  "newFileFolderPath": "00 Inbox",
   "showUnsupportedFiles": true
 }
\ No newline at end of file
diff --git a/.obsidian/plugins/obsidian-file-color/data.json b/.obsidian/plugins/obsidian-file-color/data.json
index 587ba26..aeb5ea2 100644
--- a/.obsidian/plugins/obsidian-file-color/data.json
+++ b/.obsidian/plugins/obsidian-file-color/data.json
@@ -1,5 +1,5 @@
 {
-  "cascadeColors": false,
+  "cascadeColors": true,
   "colorBackground": false,
   "palette": [],
   "fileColors": []
diff --git a/00 Inbox/29612838 - Lecture - 21_04.md b/00 Inbox/29612838 - Lecture - 21_04.md
new file mode 100644
index 0000000..09436d5
--- /dev/null
+++ b/00 Inbox/29612838 - Lecture - 21_04.md	
@@ -0,0 +1,27 @@
+---
+created: 2026-04-21 13:18
+course: "[[29592673 - Elektrotechnik II]]"
+topic:
+related:
+type: lecture
+status: 🔴
+tags:
+  - university
+---
+## 📌 Summary
+
+> [!abstract]
+> 
+
+---
+
+## 📝 Content
+
+## Komplexer Momentanwert 
+
+$i(t) = hat(i) e^(j(omega t + phi)) = hat(i) cos(omega t + phi) + j hat(i) sin(omega t + phi)$
+=> $i(t) = "Im"{i(t)}$ 
+
+## Komplexe Kontenregel
+$sum_"Knoten" "Im"{underline(i)(t)} = 0$ 
+=> $"Im" { sum_"Knoten" underline(i)(t) } = 0$
diff --git a/40 Extras/OOP/die_einen_da b/40 Extras/OOP/die_einen_da
new file mode 160000
index 0000000..e3a86db
--- /dev/null
+++ b/40 Extras/OOP/die_einen_da	
@@ -0,0 +1 @@
+Subproject commit e3a86db2d1350899229253b7ea0dd937b7c3f414