diff --git a/doc/latexmath.txt b/doc/latexmath.txt
index 6f04321..9334387 100644
--- a/doc/latexmath.txt
+++ b/doc/latexmath.txt
@@ -118,4 +118,10 @@ Renders:
 \right] \]
 ++++++++++++++++++++++++++++++++++++++++++++
 
+Books with latexmath
+--------------------
 
+* https://github.com/edusantana/calculo-diferencial-e-integral-livro/releases[This
+is a PDF book about mathematics], written in portuguese. You can see the
+https://github.com/edusantana/calculo-diferencial-e-integral-livro/tree/master/livro/capitulos[code
+here].
diff --git a/docbook45.conf b/docbook45.conf
index 76cbd0f..e84568c 100644
--- a/docbook45.conf
+++ b/docbook45.conf
@@ -20,6 +20,7 @@ backend-docbook=
 # toc and numbered are set to maintain original default behavior.
 toc=
 numbered=
+edition=
 
 [replacements2]
 # Line break markup. Custom processing instruction in fo.xsl.
@@ -692,6 +693,9 @@ template::[header-declarations]
 <book lang="{lang=en}">
 <bookinfo>
 template::[docinfo]
+# If you have specified the edition in your docinfo,
+# docbook uses the last one, defined here:
+{edition? <edition>{edition}</edition>}
 </bookinfo>
 
 [footer]