Warning Underfull \hbox (badness 6510) in paragraph

Question

I get a warning while citing an article in my bibliography:

Warning : Underfull \hbox (badness 6510) in paragraph at lines 618--619

in my latex file.

 \documentclass[a4paper,12pt]{report}
 \begin{document}

 \begin{thebibliography}{00}

 \bibitem{backpropagation}
  Rumelhart, D., Hinton, G. \& Williams, R. Learning representations by back-propagating errors. Nature 323,533–536 (1986). https://doi.org/10.1038/323533a0

 \end{thebibliography}
 \end{document}

How do I solve this?

Answer 1

The problem is that your doi does not break lines. To avoid this, you could use the xurl package:

 \documentclass[a4paper,12pt]{report}
 
  \usepackage{xurl}
 
 
 \begin{document}

 \begin{thebibliography}{00}


 \bibitem{backpropagation}
  Rumelhart, D., Hinton, G. \& Williams, R. Learning representations by back-propagating errors. Nature 323,533–536 (1986). \url{https://doi.org/10.1038/323533a0}

 \end{thebibliography}
 \end{document}

If this line break in the middle of the link is too aggressive, you could also try the url or hyperref package:

 \documentclass[a4paper,12pt]{report}
 
  \usepackage{url}
 
 
 \begin{document}

 \begin{thebibliography}{00}


 \bibitem{backpropagation}
  Rumelhart, D., Hinton, G. \& Williams, R. Learning representations by back-propagating errors. Nature 323,533–536 (1986). \url{https://doi.org/10.1038/323533a0}

 \end{thebibliography}
 \end{document}