diff --git a/semester3/analysis-ii/analysis-ii-cheat-sheet.tex b/semester3/analysis-ii/analysis-ii-cheat-sheet.tex
index 60b9da7..8366731 100644
--- a/semester3/analysis-ii/analysis-ii-cheat-sheet.tex
+++ b/semester3/analysis-ii/analysis-ii-cheat-sheet.tex
@@ -75,7 +75,9 @@ And yes, she did really miss an opportunity there with the quote\dots But she wa
 \input{parts/diffeq/linear-ode/00_intro.tex}
 \input{parts/diffeq/linear-ode/01_order-one.tex}
 \input{parts/diffeq/linear-ode/02_constant-coefficient.tex}
-% \input{parts/diffeq/linear-ode/}
+
+\section{Differential Calculus in Vector Space}
+\input{parts/vectors/differentiation/00_intro.tex}
 
 
 
diff --git a/semester3/analysis-ii/parts/diffeq/linear-ode/04_other-methods.tex b/semester3/analysis-ii/parts/diffeq/linear-ode/04_other-methods.tex
deleted file mode 100644
index e69de29..0000000
diff --git a/semester3/analysis-ii/parts/diffeq/linear-ode/03_harmonic-oscilator.tex b/semester3/analysis-ii/parts/vectors/differentiation/00_intro.tex
similarity index 100%
rename from semester3/analysis-ii/parts/diffeq/linear-ode/03_harmonic-oscilator.tex
rename to semester3/analysis-ii/parts/vectors/differentiation/00_intro.tex
diff --git a/semester3/analysis-ii/parts/vectors/differentiation/intro.tex b/semester3/analysis-ii/parts/vectors/differentiation/intro.tex
deleted file mode 100644
index e69de29..0000000