diff --git a/electives/others/amr/autonomous-mobile-robots-cheatsheet.pdf b/electives/others/amr/autonomous-mobile-robots-cheatsheet.pdf
index af77608..63961d0 100644
Binary files a/electives/others/amr/autonomous-mobile-robots-cheatsheet.pdf and b/electives/others/amr/autonomous-mobile-robots-cheatsheet.pdf differ
diff --git a/electives/others/amr/autonomous-mobile-robots-cheatsheet.tex b/electives/others/amr/autonomous-mobile-robots-cheatsheet.tex
index f43787e..2e9a19b 100644
--- a/electives/others/amr/autonomous-mobile-robots-cheatsheet.tex
+++ b/electives/others/amr/autonomous-mobile-robots-cheatsheet.tex
@@ -64,7 +64,7 @@
 \section{Multi-Sensor Estimation}
 \input{parts/03_multi-sensor-estimation/00_linearization.tex}
 \input{parts/03_multi-sensor-estimation/01_least-squares.tex}
-% \input{parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex}
+\input{parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex}
 % \input{parts/03_multi-sensor-estimation/}
 
 \end{document}
diff --git a/electives/others/amr/parts/03_multi-sensor-estimation/01_least-squares.tex b/electives/others/amr/parts/03_multi-sensor-estimation/01_least-squares.tex
index 30838a9..b51d0da 100644
--- a/electives/others/amr/parts/03_multi-sensor-estimation/01_least-squares.tex
+++ b/electives/others/amr/parts/03_multi-sensor-estimation/01_least-squares.tex
@@ -1,4 +1,10 @@
 \subsection{Linear Least Squares}
 \bi{Goal}: $\argmin{x \in \R^n} ||\mat{A}\vec{x} - b||^2_2$, $\mat{A}$: rows $i$-th datap. col $c$: $t_i^{c - 1}$.
 
-\bi{Man. sol.}: comp. $M = A^\top A$, $b' = A^\top b$, then $Mx = b'$
+\bi{Man. sol.}: comp. $M = A^\top A$, $b' = A^\top b$, then $Mx = b'$.
+
+\bi{Prob. sol.}: $\text{argmax} p(\vec{x} \divider \vec{z})$ with
+\begin{itemize}
+    \item \bi{Max. Like} $p(\vec{x} | \vec{z}) \propto p(\vec{z} | \vec{x}) = \prod_{i = 1}^N p(\vec{z}_i | \vec{x})$
+    \item \bi{M a Post} $p(\vec{x} | \vec{z}) \propto p(\vec{z} | \vec{x}) p(\vec{x}) = p(\vec{x}) \prod_{i = 1}^N p(\vec{z}_i | \vec{x})$
+\end{itemize}
diff --git a/electives/others/amr/parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex b/electives/others/amr/parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex
index e69de29..9ea0740 100644
--- a/electives/others/amr/parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex
+++ b/electives/others/amr/parts/03_multi-sensor-estimation/02_nonlinear-least-squares.tex
@@ -0,0 +1,6 @@
+\subsection{Non-Linear Least Squares}
+Find $\vec{x}^* = \text{argmax} p(\vec{x} | \vec{z}) = \argmin{}(-\log(p(\vec{x}|\vec{z})))$
+
+\bi{Gauss-Newton}
+
+\bi{Levenberg-Marquardt}