# Is it possible to allow linebreaks in the ISBN number of (auto-generated) bibliography files?

I hope it's not a duplicate but I was not able to find a solution. I generate my *.bib file using Citavi. The problem is, that if the ISBN number is near the end of the line it generates overfull hboxes, because there is no automatic linebreak within the number (even not at the hyphens).

I use this header:

\usepackage[
backend=biber,
style=alphabetic,
backref=true]
{biblatex}
\DeclareNameAlias{sortname}{last-first} % Change order of names in bibliography
\DeclareNameAlias{default}{last-first}  % Change order of names in bibliography
\makeatletter
\makeatother


The entry in the *.bib file is:

@book{Hahn.2002,
author = {Hahn, Hubert},
year = {2002},
title = {{Rigid Body Dynamics of Mechanisms}},
publisher = {Springer-Verlag},
isbn = {978-3-642-07617-6},
volumes = {2},
subtitle = {{1 Theoretical Basis}},
location = {Berlin and Heidelberg and New York},
pagetotal = {336},
file = {http://gso.gbv.de/DB=2.1/PPNSET?PPN=77292189X}
}


which generates

If I add a manual space in the number, I get the desired result

 isbn = {978-3-642- 07617-6},


But it would be much nicer with an automatic solution which does not produce overfull boxes.

MWE (LuaLaTex):

\documentclass[a4paper]{scrbook}
\usepackage{polyglossia}    % instead of babel
\setdefaultlanguage[]{english}
\usepackage[english]{hyperref}
\usepackage{csquotes}% Recommended: http://tex.stackexchange.com/questions/5091/what-to-do-to-switch-to-biblatex
\usepackage{fontspec}
\setromanfont{Cambria}
\setsansfont{Calibri}

\usepackage[%style=numeric-comp, backend=biber]{biblatex}
backend=biber, %    natbib=true,
sorting=ynt,  % year, name, title
backref=true]
{biblatex}
\DeclareNameAlias{sortname}{last-first} % Change order of names in bibliography
\DeclareNameAlias{default}{last-first}  % Change order of names in bibliography

\begin{filecontents}{\jobname.bib}
@book{Hahn.2002,
author = {Hahn, Hubert},
year = {2002},
title = {{Rigid Body Dynamics of Mechanisms}},
publisher = {Springer-Verlag},
isbn = {978-3-642- 07617-6},
volumes = {2},
subtitle = {{1 Theoretical Basis}},
location = {Berlin and Heidelberg and New York},
pagetotal = {336},
file = {http://gso.gbv.de/DB=2.1/PPNSET?PPN=77292189X}
}
@book{Hahn.2012,
author = {Hahn, Hubert},
year = {2012},
title = {{Rigid Body Dynamics of Mechanisms}},
publisher = {Springer-Verlag},
isbn = {978-3-642-07617-6},
volumes = {2},
subtitle = {{1 Theoretical Basis}},
location = {Berlin and Heidelberg and New York},
pagetotal = {336},
file = {http://gso.gbv.de/DB=2.1/PPNSET?PPN=77292189X}
}
\end{filecontents}

\begin{document}
ABC
\nocite{*}
\printbibliography
\end{document}


Thanks a lot for help!

• It is a lualatex problem. It doesn't insert hyphenation points at the hyphen when numbers are involved. (I don't know why). Feb 24, 2015 at 15:01
• @UlrikeFischer Interesting. It works if you make digits letters according to the hyphenation system (ie make them lowercase to themselves) luatex breaks 978-3-642-07617-6 if you add \lccode0=0 \lccode1=1 \lccode2=2 \lccode3=3 \lccode4=4 \lccode5=5 \lccode6=6 \lccode7=7 \lccode8=8 \lccode9=9 Feb 24, 2015 at 20:08
• Issue reported to the LuaTeX team: tug.org/pipermail/luatex/2015-February/005074.html Feb 24, 2015 at 21:34
• The bug report tracker.luatex.org/view.php?id=925 suggests that this issue was resolved and should have disappeared in LuaTeX 0.80.0. So I'm inclined to vote to close. Apr 5, 2015 at 16:15
• I have updated the LuaTeX package now (miktex-luatex-bin-2.9; 3/25/2015), but the error is still the same (in my case). Apr 7, 2015 at 14:45