Bibliographic reference in Latex

Question

I’m trying to create a file .bib, but my file .tex only displays the first. What I’m doing wrong?

@book{Boaventura,
  title={Grafos: Teorias, modelos, algoritmos},
  author={Boaventura Netto, P. O.},
  isbn={9788521203919},
  url={http://www.blucher.com.br/produto/03919/grafos:-teoria-modelos-algoritmos-4-edicao-revista-e-ampliada},
  year={2006},
  publisher={Blucher}
}

@book{Ziviani,
  title={Projetos de Algoritmos com implementações em Pascal e C},
  author={Ziviani, N.},
  isbn={9788522110506},
  url={http://www2.dcc.ufmg.br/livros/algoritmos/index.php},
  year={2011},
  publisher={Cengage Learning}
}

Answer 1

I tried your Bibtex and it worked well.

\documentclass[portuges,a4paper]{article}
\usepackage{babel}
\usepackage[utf8]{inputenc}
\begin{document}

\cite{Ziviani}

\bibliographystyle{alpha}          % ou plain ou ...
\bibliography{patricia}            % patricia.bib
\end{document}

So I take it you’re missing the \cite{...}. If that is not the case, add a micro example with your text.

Sometimes, for the debug phase of Bibtex, place \nocite{*} can be useful (pours all bibliography without citations)