# Bibliography brackets are empty

Somehow my Biblatex isnt working with alphabetical style.

Numerical style is working normally. My header looks like this:

\usepackage[
backend=biber,
style=alphabetic,
citestyle=authoryear
]{biblatex}
%


citing with:

\cite{bsi}


and my .bib file looking like this:

@online{bsi,
ALTauthor = {Bundesamt für Sicherheit in der Informationstechnik},
title = {Cloud Computing Grundlagen},
urldate = {2019-11-14},
url = {https://www.bsi.bund.de/DE/Themen/DigitaleGesellschaft/CloudComputing/Grundlagen/Grundlagen_node.html}
}


Any ideas what might be the problem?

• biblatex generates the alphabetic label from the author/editor/translator and year field (it can fall back to label or shorthand). None of those fields are populated here, so biblatex has nothing to go by. Dec 5, 2019 at 16:52
• Try author = {{Bundesamt für Sicherheit in der Informationstechnik}}, shortauthor = {BSI},. (I couldn't find a sensible year of publication on the site) Dec 5, 2019 at 16:53
• Unless you have additional options, I would not recommend the style mixture style=alphabetic, citestyle=authoryear. Either take style=authoryear, or go with style=alphabetic. A mixture of the two is just confusing and inconsistent. Dec 5, 2019 at 16:55
• Thanks very much. It's working now. I was assuming, that the reference name is used in the bracket. Dec 5, 2019 at 19:38

The standard definition for alphabetic labels tries to take the labelname field (one of author, editor, translator) and the date/year and combine the two into a combination along the lines of "SR98". One can use the label field to override the labelname part of the label or shorthand to override the complete label.

In the example entry none of the mentioned fields are filled, so biblatex does not manage to generate any label from the entry. It is at least possible to give the author, so I'd suggest something like

\documentclass[ngerman]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

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

\begin{filecontents}{\jobname.bib}
@online{bsi,
author      = {{Bundesamt für Sicherheit in der Informationstechnik}},
shortauthor = {BSI},
title       = {Cloud Computing Grundlagen},
url         = {https://www.bsi.bund.de/DE/Themen/DigitaleGesellschaft/CloudComputing/Grundlagen/Grundlagen_node.html},
urldate     = {2019-11-14},
}
\end{filecontents}

The entry key (bsi) should be thought of as a purely internal label. None of the common standard styles will ever use the entry key in the output.