--- doc/doxygen_manual.tex.orig	2019-08-04 11:51:41 UTC
+++ doc/doxygen_manual.tex
@@ -22,7 +22,7 @@
 \usepackage{array}[=2016-10-06]
 \fi
 %%
-\usepackage[a4paper,left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm]{geometry}
+\usepackage[left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm]{geometry}
 \usepackage{makeidx}
 \usepackage{natbib}
 \usepackage{graphicx}