# Biblatex not showing ISBN with apa style

I have taken this example from BibTex - Show ISBN number?:

\documentclass{article}

\usepackage[american]{babel}  %% added in a recent edit
\usepackage[backend=biber]{biblatex}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@book{QueueSystems,
author    = "Leonard Kleinrock",
maintitle = "Queueing Systems",
volume    = "1",
title     = "Theory",
publisher = "Wiley-Interscience",
year      = "1975",
ISBN      = "0471491101",
}
\end{filecontents}

\nocite{*}

\begin{document}

\printbibliography

\end{document}


which works well as long as I do not specify the apa format. If I add the style=apa after backend=biber, it stops showing the ISBN entry. what should I do to make this example show the ISBN ? I tested adding \DeclareLanguageMapping{american}{american-apa} but to no avail. My installation of biblatex is very recent (version 3.3) and biber is version 2.4.

• As per the package docs, add a babel line before loading biblatex - \usepackage[american]{babel} – PLK Apr 4 '16 at 21:32
• True, adding \usepackage[american]{babel} allowed the document to compile. However, I still don't see the ISBN. Looking in the .bbl file, I do see the isbn fields \field{isbn}{0471491101}. So it does not completely answer the problem. Would it be possible that the apa format is outdated? the file american-apa.lbx is date 2016/03/01... – Denis Cousineau Apr 5 '16 at 1:57
• You have two unrelated problems here. The first one is the standard "you are missing \DeclareLanguageMapping" error, the second is that you don't get to see the ISBN. Since you are aware of the \DeclareLanguageMapping issue yourself, maybe you want to clean up your question to drop this, it is a red herring, but seems to have confused people trying to answer. – moewe Apr 5 '16 at 8:11
• Showing ISBN is not part of APA style, that's why it's not implemented. – PLK Apr 5 '16 at 10:19

As far as I can see biblatex-apa just doesn't print the ISBN (from that I would infer that APA style does not require the inclusion of ISBNs - indeed, PLK confirms this in his comment). If you must have ISBNs you can modify the doi+eprint+url

\renewbibmacro*{doi+eprint+url}{%
\printfield{isbn}%
\newunit\newblock
\iftoggle{bbx:doi}
{\printfield{doi}%
\iffieldundef{doi}{}{\renewcommand*{\finentrypunct}{\relax}}}
{}%
\newunit\newblock
\iftoggle{bbx:eprint}
{\usebibmacro{eprint}%
\iffieldundef{eprint}{}{\renewcommand*{\finentrypunct}{\relax}}}
{}%
\newunit\newblock
\iftoggle{bbx:url}
{\usebibmacro{url+urldate}%
\iffieldundef{url}{}{\renewcommand*{\finentrypunct}{\relax}}}
{}}


With this change you could forfeit APA compliance, so make sure you really need to show the ISBN.

• Thanks @moewe for setting the record straigth: APA indeed does not show ISBN. My mistake here. Thanks also for this answer and the note of caution: If one really wants to show ISBN, it shows how it can be done. – Denis Cousineau Apr 6 '16 at 1:03

I do not get an error. I am using latest Debian. I copied and pasted your code into Texstudio, and viewed pdf, showing the citation with ISBN number.

I added the style=apa so that:

\usepackage[backend=biber, style=apa]{biblatex}


and still no error.

• Hum... I use MiKTeX version 2.9. – Denis Cousineau Apr 5 '16 at 2:27
• Are you sure you are still seeing the ISBN with style=apa? I have the current version (2016/03/01 v6.8) and don't get to see the ISBN. – moewe Apr 5 '16 at 8:10
• Have rerun, still seeing the ISBN. Texstudio is 2,10,8 Biblatex is 3.3, dated March 8 2016 – ozhank Apr 5 '16 at 10:36
• What is your biblatex-apa version though? As I said I don't get the ISBN with style=apa and PLK (the developer) confirms this behaviour in his comments above. – moewe Apr 5 '16 at 12:15

The values are to be given within braces.

\documentclass{article}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@book{QS:1,
author    = {Leonard Kleinrock},
maintitle = {Queueing Systems},
volume    = {1},
title     = {Theory},
publisher = {Wiley-Interscience},
year      = {1975},
isbn     = {0471491101},
}
\end{filecontents}
\usepackage[backend=bibtex,sorting=none]{biblatex}

• Although I do prefer to wrap fields in braces and not in quotation marks you will find that you example still works if you use " instead of {...}. The issue here is the biblatex-apa style and not the field delimiters. " and {...} are largely equivalent ... – moewe Apr 5 '16 at 8:03