diff --git a/S2/AnaMech/VL/AnMeVL3.typ b/S2/AnaMech/VL/AnMeVL3.typ
index c39c61c..69cebb2 100644
--- a/S2/AnaMech/VL/AnMeVL3.typ
+++ b/S2/AnaMech/VL/AnMeVL3.typ
@@ -81,4 +81,7 @@ Folgern von allgemeinen Aussagen ohne Rechnen
 
 = Periodische Bahnen
 
-Fuer kleine Schwingungen entw
+Fuer kleine Schwingungen entwickle $V (x)$ um $x_0 $ (Position des Minimums)
+$
+	v (x)= v (x_0 )+1/2 V'' (x_0 ) (x-x_0 )^2 +1/6 V''' (x_0 ) (x-x_0 )^3 +1/24 V'''' (x_0 ) (x-x_0 )^(4) + ...
+$
diff --git a/book.typ b/book.typ
index d4dc61e..b0eef92 100644
--- a/book.typ
+++ b/book.typ
@@ -17,20 +17,20 @@
   summary: [ // this field works like summary.md of mdbook
 
     = ExPhy II
-    - #chapter("S2/ExPhyII/VL/ExIIVL1.typ")[ExPhy II]
-	- #chapter("S2/ExPhyII/VL/ExIIVL2.typ")[ExPhy II]
+    - #chapter("S2/ExPhyII/VL/ExIIVL1.typ")[VL1]
+	- #chapter("S2/ExPhyII/VL/ExIIVL2.typ")[VL2]
 
     = CWR
-    - #chapter("S2/CWR/VL/CwrVL1.typ")[CWR]
-	- #chapter("S2/CWR/VL/CwrVL2.typ")[CWR]
+    - #chapter("S2/CWR/VL/CwrVL1.typ")[VL1]
+	- #chapter("S2/CWR/VL/CwrVL2.typ")[VL2]
 
     = AnaMech
     - #chapter("S2/AnaMech/VL/AnMeVL1.typ")[VL1]
 	- #chapter("S2/AnaMech/VL/AnMeVL3.typ")[VL3]
 
     = Diff II
-	- #chapter("S2/DiffII/VL/DiIIVL1.typ")[Diff II]
-	- #chapter("S2/DiffII/VL/DiIIVL2.typ")[Diff II]
+	- #chapter("S2/DiffII/VL/DiIIVL1.typ")[VL1]
+	- #chapter("S2/DiffII/VL/DiIIVL2.typ")[VL2]
   ]
 
 )