I've been puzzling with this for hours now and I can't solve it. I'm using LyX for my article and I made a BibTeX file with JabRef. I inserted the BibTeX bibliography into LyX, but when I try to compile, errors appear:

Multiple "Missing $ inserted.", "Missing } inserted." and "Extra }, or forgotten \endgroup."

The first error says:

Missing $ inserted.
\newblock http://www.nasa.gov/mission_

They all refer to lines in the auto-generated .bbl file.

The same problem occurs when I export LyX to LaTeX and compile it there (also with different encodings). I've read some things about BibTeX encoding, but I can't figure it out.

I'll post some of the BibTeX below:

  author = "Jens N. Kaftan and Andr{\'e} A. Bell and Til Aach",
  title = "Mean Shift Segmentation Evaluation of Optimization Techniques",
  booktitle = "Proceedings of the Third International Conference on Computer Vision Theory and Applications, VISAPP 2008",
  year = "2008",
  pages = "365-374",
  address = "Funchal, Madeira - Portugal",
  month = "January 22-25",
  publisher = "INSTICC - Institute for Systems and Technologies of Information, Control and Communication"

  author = "Kawakita, M. and Kurita, T. and Kikuchi, H. and Inoue, S.",
  title = "HDTV axi-vision camera",
  booktitle = "Proc. of International Broadcasting Conference",
  year = "2002",
  pages = "397-404"

  author = "Marr, D. and Poggio, T.",
  title = "A computational theory of human stereo vision",
  journal = "Proceedings of the Royal Society of London. Series B, Biological Sciences",
  year = "1979",
  volume = "204",
  pages = "301-328",
  number = "1156",
  issn = "0080-4649",
  publisher = "JSTOR"

  author = "Pangburn, Brian E. and Ayo, Jonathan P.",
  title = "Koders - Source Code Search Engine",
  howpublished = "http://www.koders.com/info.aspx?c=ProjectInfo\&pid=1ZLCBNBRKBWSX9KL1VF3ZA989H\&s=Region",
  year = "2002",
  timestamp = "2011.01.06"

Any ideas?

1 Answer 1


The problem is with the underscore in the url. Try using something like

howpublished = "\url{http://www.nasa.gov/mission_pages/stereo/multimedia/deploy.html}"

or, even better,

url = "http://www.nasa.gov/mission_pages/stereo/multimedia/deploy.html"

in your .bib file. You should also add to your main .tex file \usepackage{url} or \usepackage{hyperref} (bot not both!).

  • 1
    Thanks. The second notation works, but it will not show the url in the reference list in the final PDF. Neither does the first notation. Commented Jan 9, 2011 at 15:48
  • 2
    I now added backslashes before each underscore and it works. Commented Jan 9, 2011 at 15:53
  • It depends on the .bib style that you are using. Anyway, the first notation should probably work in most cases. You also need to load either url or the hyperref package. Commented Jan 10, 2011 at 12:16
  • What fixed this for me was actually commenting out my \usepackage{url} line. I was using that and \usepackage{hyperref} together peaceably before, but the url in the bibtex entry made them fight, I guess.
    – chbrown
    Commented Dec 13, 2012 at 1:58

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