# biblatex - issue number of journal in date

I am building a bibliography using biblatex and biber (\usepackage[backend=biber,minnames=2,backref,firstinits,sortcites]{biblatex}) with a lot of cited papers. Therefore I often have the case of a journal name, volume, issue, month and year, all necessary.

Now the strange thing is, if I have a bibitem such as:

@article{item,
title = {Some Nice Scientific Title},
author = {Doe, Jane},
journal = {Important Journal},
volume = {50},
issue = {20},
pages = {1877--1879},
year = {1984},
month = {Jun},
publisher = {Important Society},
doi = {00.0000}
}


the bibliography looks like this:

Can you spot it? The issue number 20 is in the brackets with the date. Now it looks like it is the day in the date.

So, how do I get around this?

Here's the full MWE:

\documentclass{scrartcl}

\usepackage[backend=biber,minnames=2,backref,firstinits,sortcites]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{item.bib}
@article{item,
title = {Some Nice Scientific Title},
author = {Doe, Jane},
journal = {Important Journal},
volume = {50},
issue = {20},
pages = {1877--1879},
year = {1984},
month = {Jun},
publisher = {Important Society},
doi = {00.0000}
}
\end{filecontents}

\begin{document}

\nocite{*}

\end{document}

• Use the number field and not issue. While many journals call the 'subdivision' of a volume 'issue', biblatex uses number here. issue is meant for more concrete names such as 'Summer issue'. – moewe Feb 20 '17 at 14:56
• @moewe Huh, as simple as that... Thanks! (Maybe someone should tell the publishers who offer citation downloads...) Is this some sort of remnant from the bibtex past? – Taunch Feb 20 '17 at 14:59
• @Taunch - You asked, "Is this some sort of remnant from the bibtex past?" The answer is, "Almost certainly not." Virtually all bibliography style files are programmed to recognize and process a field called number if it occurs in an entry of type @article, but hardly any of them would even know what to make of a field called issue. – Mico Feb 20 '17 at 15:45

You need to use the number field and not issue. While many journals call the 'subdivision' of a volume 'issue', biblatex uses number here. issue is meant for more concrete names such as 'Summer issue'.

Refer also to the biblatex manual, which for issue has to say on page 20

This field [issue] is intended for journals whose individual issues are identified by a designation such as ‘Spring’ or ‘Summer’ rather than the month or a number. [...]

the field number is characterised as (p. 21)

The number of a journal or the volume/number of a book in a series.

As far as I am aware it has been this way since the good ol' BibTeX times. Indeed btxdoc (§ 3.2, p. 10) describes the number field as (emphasis mine)

The number of a journal, magazine, technical report, or of a work in a series. An issue of a journal or magazine is usually identified by its volume and number; the organization that issues a technical report usually gives it a number; and sometimes books are given numbers in a named series.

Some citation download tools on the web use issue inappropriately where number should be used. That is one of the reasons why you should always check downloaded entries thoroughly manually.

The following Biber sourcemap maps issue to number and then deletes it if the field only contains a number

\DeclareSourcemap{
\maps[datatype=bibtex]{
\map{
\step[fieldsource=issue, match=\regexp{\A[0-9]+\Z}, final]
\step[fieldset=number, origfieldval]
\step[fieldset=issue, null]
}
}
}

• +1 for "you should always check downloaded entries thoroughly manually". :-) – Mico Feb 20 '17 at 15:09