diff --git a/chapters/infrastructure.tex b/chapters/infrastructure.tex
index b49814d..f3bc0a4 100755
--- a/chapters/infrastructure.tex
+++ b/chapters/infrastructure.tex
@@ -21,6 +21,17 @@ Au niveau des composants destinés à épauler ces applications, nous pouvons di
     \textbf{Les composants de supervision}, qui permettent de s'assurer que tout fonctionne correctement, et qu'aucun incident n'est prévu ou n'a été constaté récemment.
 \end{enumerate}
 
+\textit{Designing for production} means thinking about production issues as first-class concerns: \cite[pp. 142-143]{release_it}:
+
+\begin{itemize}
+  \item \textbf{Operations}: Security, availablity, capacity, status, communication,
+  \item \textbf{Control plane}: Monitoring, deployment, anomaly detection, new features
+  \item \textbf{Interconnect}: Routing, load balancing, failover, traffic management
+  \item \textbf{Instances}: Services, processes, components, instance monitoring
+  \item \textbf{Foundation}: Hardware, VMs, IP addresses, physical network.
+\end{itemize}
+
+
 \section{Composants fonctionnels}
 
 \begin{figure}[H]
@@ -164,6 +175,19 @@ Au niveau logiciel (la partie mise en subrillance ci-dessus), la requête arrive
 
 https://circus.readthedocs.io/en/latest/, https://uwsgi-docs.readthedocs.io/en/latest/, statsd
 
+\begin{quote}
+When we crash an actor or a process, how does a new one get started ?
+You could write a bash script with a while() loop in it.
+But what happens when the problem persists across restarts ?
+The script basically fork-bombs the server. \cite[p. 109-110]{release_it}
+\end{quote}
+
+Actors system use a hierarchical tree of supervisors to manage the restarts.
+Whenever an actor terminates, the runtime notifies the supervisor.
+The supervisor can then decide to restart the child actor, restart all of its children, or crash itself.
+If the supervisor crashes, the runtime will terminate all its children and notify the supervisor's supervisor.
+Ultimately you can get while branches of the supervision tree to restart with a clean state.
+
 
 \subsection{Journaux d'évènements}
 
diff --git a/chapters/python.tex b/chapters/python.tex
index 6f2cc6d..00af56d 100755
--- a/chapters/python.tex
+++ b/chapters/python.tex
@@ -1064,7 +1064,9 @@ Cet élément peut être:
 
 \subsubsection{Ignorer une ligne de code}
 
+\begin{listing}
 
+\end{listing}
 
 \subsubsection{Ignorer un bloc de code}
 
diff --git a/references.bib b/references.bib
index fdd8d7d..37dd6e7 100755
--- a/references.bib
+++ b/references.bib
@@ -100,6 +100,10 @@
    isbn = {978-1-449-37332-0},
    release = {Fifteenth release - 2021-03-26}
 }
+@book{release_it,
+   title = {Release It!},
+   author = {Michael T. Nygard}
+}
 @book{rework,
 	title = {Rework},
 	author = {David Heinemeier Hansson and Jason Fried},