\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}  % allows UTF encoding, needed for Icelandic characters
\usepackage[backend=biber, bibencoding=utf8, style=apa]{biblatex}
\usepackage[american]{babel}
\DeclareLanguageMapping{american}{american-apa}  % after biblatex and babel
\addbibresource{references.bib}

\begin{document}
\nocite{*}

\printbibliography{}
\end{document}

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