There is an option without additional packages that works under pdflatex
Adapt this code
\begin{figure}[h]
\centering
\includegraphics[width=\ScaleIfNeeded]{figuras/diagrama-spearman.pdf}
\caption{Schematical view of Spearman's theory.}
\end{figure}
"diagrama-spearman.pdf" is a plot generated with TikZ and this is the code (it is another .tex file different from the .tex file where I want to insert a pdf)
\documentclass[border=3mm]{standalone}
\usepackage[applemac]{inputenc}
\usepackage[protrusion=true,expansion=true]{microtype}
\usepackage[bb=lucida,bbscaled=1,cal=boondoxo]{mathalfa}
\usepackage[stdmathitalics=true,math-style=iso,lucidasmallscale=true,romanfamily=bright]{lucimatx}
\usepackage{tikz}
\usetikzlibrary{intersections}
\newcommand{\at}{\makeatletter @\makeatother}
\begin{document}
\begin{tikzpicture}
\tikzset{venn circle/.style={draw,circle,minimum width=5cm,fill=#1,opacity=1}}
\node [venn circle = none, name path=A] (A) at (45:2cm) { };
\node [venn circle = none, name path=B] (B) at (135:2cm) { };
\node [venn circle = none, name path=C] (C) at (225:2cm) { };
\node [venn circle = none, name path=D] (D) at (315:2cm) { };
\node[above right] at (barycentric cs:A=1) {logical};
\node[above left] at (barycentric cs:B=1) {mechanical};
\node[below left] at (barycentric cs:C=1) {spatial};
\node[below right] at (barycentric cs:D=1) {arithmetical};
\node at (0,0) {G};
\end{tikzpicture}
\end{document}
This is the diagram I included
