\documentclass[english]{memoir}
\usepackage{babel}
\usepackage{roffe}
\usepackage[backend=biber,date=short,maxcitenames=2,style=apa]{biblatex}

\DeclareLanguageMapping{norsk}{norsk-apa}
\DeclareLanguageMapping{english}{american-apa}
\addbibresource{Papers2.bib}
\addbibresource{R.bib}

\begin{document}
\cite{R-base}

\printbibliography
\end{document}