If I use the bibstyle=authoryear really weird black squares appear. How can I get rid of them? Here's a screenshot of the squares:

Strange black squares

This are some citations:

 author = {Jouhara, Hussam and {\.Z}abnie{\'n}ska-G{\'o}ra, Alina and Khordehgah, Navid and Doraghi, Qusay and Ahmad, Lujean and Norman, Les and Axcell, Brian and Wrobel, Luiz and Dai, Sheng},
 year = {2021},
 title = {Thermoelectric generator (TEG) technologies and applications},
 pages = {1--18},
 volume = {9},
 issn = {26662027},
 journal = {International Journal of Thermofluids},
 doi = {10.1016/j.ijft.2021.100063}

 author = {Kang, Chang-Jong and Kotliar, Gabriel},
 year = {2018},
 title = {Study for material analogs of FeSb2 : Material design for thermoelectric materials},
 urldate = {3/3/2021},
 Pages = {1--12},
 volume = {2},
 number = {3},
 journal = {Physical Review Materials},
 doi = {10.1103/PhysRevMaterials.2.034604}

This are the packages I'm using:

\usepackage[babel, german=guillemets]{csquotes}
\usepackage[backend=biber, citestyle=authoryear-icomp, bibstyle=authoryear, sorting=nyt, hyperref=true, uniquename=false, maxcitenames=2, maxbibnames=3]{biblatex}
\DefineBibliographyStrings{ngerman}{andothers={et\addabbrvspace al\adddot},}

\autocite{Kang.2018} \autocite{Jouhara.2021}
  • 1
    Welcome to TSE. Please post a Minimal Working Example, instead of a code snippet. Aug 29, 2021 at 17:18
  • Done @JoséCarlosSantos
    – Hanna
    Aug 29, 2021 at 17:22
  • 2
    This looks like fancy quotation marks, which your chosen font might not support. You get the square for all unsupported glyphs.
    – Ingmar
    Aug 29, 2021 at 17:28
  • 1
    @Ingmar thanks. I changed in .tex from \usepackage[babel, german=guillemets]{csquotes} to \usepackage[babel]{csquotes} - it worked
    – Hanna
    Aug 29, 2021 at 17:42
  • 1
    A common cause of black squares instead of proper quotation marks are nesting errors. These are often caused by missing closing brackets or missing closing quotation marks. There should be an error message about this somewhere.
    – moewe
    Aug 30, 2021 at 6:30

1 Answer 1


The black square (or a similar symbol, depending on your font) often signifies a “glyph not found error”. In your case I strongly suspect typographic (“curly”) quotation marks (or perhaps «guillemets»), which your chosen font does not support.

  • 2
    For people with a similar problem: The most common cause of these black boxes from csquotes in my experience is mismatched grouping. Often it is caused by forgotten closing brackets, but if you have an active quoting character, it might also be caused by that. Do check the error messages carefully, but keep in mind that errors might only be reported several lines after they actually appeared. I have never seen these black boxes for missing characters and I could find nothing in the csquotes source that suggests csquotes uses them in that case.
    – moewe
    Aug 30, 2021 at 15:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .