diff --git a/differential-equations/electrical.bib b/differential-equations/electrical.bib
new file mode 100644
index 0000000..0f7ff5d
--- /dev/null
+++ b/differential-equations/electrical.bib
@@ -0,0 +1,9 @@
+@book{strogatz2008nonlinear,
+  title={Nonlinear Dynamics and Chaos: With Applications to Physics, Biology, Chemistry, and Engineering},
+  author={Strogatz, S.H.},
+  isbn={9780786723959},
+  series={Studies in nonlinearity},
+  url={https://books.google.es/books?id=dTvTzBeRn3cC},
+  year={2008},
+  publisher={Westview Press}
+}
diff --git a/differential-equations/electrical.pdf b/differential-equations/electrical.pdf
index ef769e2..d9c40c4 100644
Binary files a/differential-equations/electrical.pdf and b/differential-equations/electrical.pdf differ
diff --git a/differential-equations/electrical.tex b/differential-equations/electrical.tex
index 5f8c689..dffb97e 100755
--- a/differential-equations/electrical.tex
+++ b/differential-equations/electrical.tex
@@ -71,6 +71,8 @@
 % \documentclass[journal]{../sty/IEEEtran}
 
 
+\usepackage[style=numeric-comp,backend=biber,url=false]{biblatex}
+\addbibresource{electrical.bib}
 
 
 
@@ -511,7 +513,6 @@ differential, dynamics, electrical, equation, modeling, ordinary, system
 
 
 
-
 % An example of a floating figure using the graphicx package.
 % Note that \label must occur AFTER (or within) \caption.
 % For figures, \caption should occur after the \includegraphics.
@@ -621,7 +622,7 @@ The conclusion goes here.
 
 \appendices
 \section{Proof of the First Zonklar Equation}
-Appendix one text goes here.
+Appendix one text goes here. \cite{strogatz2008nonlinear}
 
 % you can choose not to have a title for an appendix
 % if you want by leaving the argument blank
@@ -659,20 +660,20 @@ The authors would like to thank...
 % http://www.ctan.org/tex-archive/biblio/bibtex/contrib/doc/
 % The IEEEtran BibTeX style support page is at:
 % http://www.michaelshell.org/tex/ieeetran/bibtex/
-%\bibliographystyle{IEEEtran}
 % argument is your BibTeX string definitions and bibliography database(s)
-%\bibliography{IEEEabrv,../bib/paper}
-%
+%\bibliographystyle{IEEEtran}
+%\bibliography{IEEEabrv,electrical}
+\printbibliography
 % <OR> manually copy in the resultant .bbl file
 % set second argument of \begin to the number of references
 % (used to reserve space for the reference number labels box)
-\begin{thebibliography}{1}
-
-\bibitem{IEEEhowto:kopka}
-H.~Kopka and P.~W. Daly, \emph{A Guide to \LaTeX}, 3rd~ed.\hskip 1em plus
-  0.5em minus 0.4em\relax Harlow, England: Addison-Wesley, 1999.
-
-\end{thebibliography}
+%\begin{thebibliography}{1}
+%
+%\bibitem{IEEEhowto:kopka}
+%H.~Kopka and P.~W. Daly, \emph{A Guide to \LaTeX}, 3rd~ed.\hskip 1em plus
+%  0.5em minus 0.4em\relax Harlow, England: Addison-Wesley, 1999.
+%
+%\end{thebibliography}
 
 % biography section
 %