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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?

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2 Answers 2

up vote 6 down vote accepted

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!).

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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. –  RemiX Jan 9 '11 at 15:48
I now added backslashes before each underscore and it works. –  RemiX Jan 9 '11 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. –  Juan A. Navarro Jan 10 '11 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 Dec 13 '12 at 1:58

I've been stuck 2 hours too with the same .bbl generation mistake. To tackle with that, I've deleted the .bib, created a new file and made sure I was referencing at least one of the papers in the bib.

Make it clean. :)

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