diff --git a/Makefile b/Makefile
index 666dc3a..ccde7a8 100644
--- a/Makefile
+++ b/Makefile
@@ -9,8 +9,8 @@ FILES = l00_diode \
 	lp_project_report \
 	l01_intro \
 	l02_esd \
-#	l03_refbias \
-	l04_afe \
+	l03_refbias \
+#	l04_afe \
 	l05_sc \
 	l06_adc \
 	l07_vreg \
diff --git a/pdf/aic.tex b/pdf/aic.tex
index 6dda890..fbbc23b 100644
--- a/pdf/aic.tex
+++ b/pdf/aic.tex
@@ -84,8 +84,8 @@ \chapter{Diodes}
 \chapter{ESD and IC}
 \input{lecture_2_-_ic_and_esd_fiximg.tex}
 
-%\chapter{References and bias}
-%\input{lecture_3_-_references_and_bias_fiximg.tex}
+\chapter{References and bias}
+\input{lecture_3_-_references_and_bias_fiximg.tex}
 
 %\chapter{Analog frontend and filter}
 %\input{lecture_4_-_analog_frontend_and_filters_fiximg.tex}
diff --git a/pdf/version.tex b/pdf/version.tex
index a4ee55e..d1901dd 100644
--- a/pdf/version.tex
+++ b/pdf/version.tex
@@ -1,2 +1,2 @@
-{\noindent Built on Thu Jan 18 14:27:55 CET 2024} \\ 
- {\noindent from 0b6a31933d049505082a2baea3c186676ee8ceaa}
+{\noindent Built on Thu Jan 18 14:34:17 CET 2024} \\ 
+ {\noindent from 6e289c68be226705a30f7454f02edfbae7a7018a}