# Biblatex-apa error message when compiling

I'm trying to write a document with APA 6th edition referencing. I'm using Texmaker 5.0.2 and Windows 10 to do so. I have been told that the biblatex-apa package is the best option for APA 6th edition referencing within LaTeX. However, when I attempt to do so I get the error:

using the MWE:

\documentclass[11pt, twoside]{article}

%document foramtting
\usepackage[margin = 2.5cm]{geometry}

%Referencing package
\usepackage[
backend = biber,
style = apa,
natbib = true
]{biblatex}

\begin{document}

This is a test for biblatex-apa. \citep{IForImagNumb,BriefHistOfeigamma,HistOfMaths}

\printbibliography

\end{document}


and the bib file

@book{HistOfMaths,
author = {Boyer, Carl B. and Merzbch, Uta C.},
year = {1991},
title = {A history of mathematics},
edition = {2nd},
city = {New York},
publisher = {Wiley}
}

@online{DrawGraph,
author = {Kummer, J.},
title = {Draw Function Graph},
url = {https://rechneronline.de/function-graphs/},
lastchecked = {2018-01-05}
}

@misc{PaintThreeD,
author = {Microsoft,},
title = {Paint 3d (Version 5.1806.20057.0) [Computer software]},
year = {2017},
publisher = {Author},
url = {https://www.microsoft.com/en-us/p/paint-3d/9nblggh5fv99}
}

@book{Elements,
author = {Euclid,},
translator = {Heath, T. L.},
editor = {Densmore, D.},
originalyear = {2002},
year = {2017},
title = {Euclid's Elements},
address = {Santa Fe, New Mexico},
publisher = {Green Lion Press}
}

@book{Cantor,
author = {Cantor, Georg},
translator = {Jourdain, Philip E. B.},
originalyear = {1915},
year = {2009},
title = {Contributions to the Founding of the Theory of Transfinite Numbers},
publisher = {BiblioLife}
}

@article{BriefHistOfeigamma,
author = {Debnath, Lokenath},
year = {2015},
title = {A brief history of the most remarkable numbers e, i, and $\gamma$ in mathematical sciences with applications},
journaltitle = {Journal of Mathematical Education in Science and Technology},
volume = {46},
issue = {6},
pages = {853-878},
doi = {10.1080/0020739X.2015.1015266}
}

@article{IForImagNumb,
author = {Curcio, Liliana},
year = {2017},
title = {I for Imaginary Numbers},
journaltitle = {Lettera Mathematica},
volume = {5},
issue = {2},
pages = {125-129},
doi = {10.1007/s40329-017-0172-6}
}

@article{PhysNatureOfImagNumb,
author = {Antonov, Alexander Alexandrovich},
year = {2016},
title = {Physical Reality and Nature of Imaginary, Complex and Hypercomplex Numbers},
journaltitle = {General Mathematics Notes},
volume = {35},
issue = {2},
pages = {40-63},
}

@article{ImagXtrmNumb,
author = {Liu, Liping},
year = {2013},
title = {Imaginary numbers for combining linear equation models via Dempster's rule},
journaltitle = {International Journal of Approximate Reasoning},
volume = {55},
issue = {1},
pages = {294-310},
doi = {10.1016/j.ijar.2013.09.004}
}


Line 19 in the error message is inbetween \printbibliography and \end{document}. I've tried deleting the whitespace, but Texmaker returns an error for line 19 (the \end{document} line).

Regards,

A LaTeX novice

biblatex-apa changes the case of @article titles from Title Case to sentence case. The case changing macro is a bit fragile and so some content like maths and other special macros need to be escaped in curly brackets.

title = {A brief history of the most remarkable numbers e, i, and {$\gamma$} in mathematical sciences with applications},


The MWE

\documentclass[11pt, twoside]{article}

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

%\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{BriefHistOfeigamma,
author = {Debnath, Lokenath},
year = {2015},
title = {A brief history of the most remarkable numbers e, i, and {$\gamma$} in mathematical sciences with applications},
journaltitle = {Journal of Mathematical Education in Science and Technology},
volume = {46},
issue = {6},
pages = {853-878},
doi = {10.1080/0020739X.2015.1015266}
}
\end{filecontents}

\begin{document}
\nocite{BriefHistOfeigamma}
\printbibliography
\end{document}


throws no error and gives the output

You may want to double check if it should be

title = {A brief history of the most remarkable numbers {$e$}, {$i$}, and {$\gamma$} in mathematical sciences with applications},


with e and i in math mode as well.

• I found that using $$..$$ instead of $..$ also works. Jul 20 '18 at 7:46
• @TorbjørnT. Oh, I didn't know - good catch, thank you. $$...$$ does not, however, protect the contents from case change: Blub $$A$$ comes out as Blub $$a$$, so the curly brackets are still needed. Jul 20 '18 at 7:50
• Ah, that I didn't try (but then I wasn't aware that case changing was the cause of the problem in the first place). Thanks. Jul 20 '18 at 7:53