\documentclass[a4paper,landscape]{minimal}
%\usepackage[a4paper,landscape]{geometry}
\usepackage{pdfpages}
\begin{document}
%\includepdf[nup=2x2,landscape,pages=1-57,column,delta=4mm 5mm,scale=0.9]{ca-einf.pdf}
%\includepdf[nup=2x2,landscape,pages=1-40,column,delta=4mm 5mm,scale=0.9]{log.pdf}
\includepdf[nup=2x2,landscape,pages=1-110,column,delta=4mm 5mm,scale=0.9]{main.pdf}
\end{document}

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: t
%%% End: