Missing $ inserted issue

Question

Trying to get my dissertation sorted (due in a few hours) and I keep getting this error:

! Missing $ inserted.
<inserted text> 
                $
l.190 ... pp. 225--236, 10.1007/978-0-387-68772-8_
                                                  18. [Online].
? 

Really struggling to sort it out.

I'm fairly new to LaTeX.

Edit: This is 189-204 of the bibtex

@inproceedings{davis,
 author = {Davis, Alan and Dieste, Oscar and Hickey, Ann and Juristo, Natalia and Moreno, Ana M.},
 title = {Effectiveness of Requirements Elicitation Techniques: Empirical Results Derived from a Systematic Review},
 booktitle = {Proceedings of the 14th IEEE International Requirements Engineering Conference},
 series = {RE '06},
 year = {2006},
 isbn = {0-7695-2555-5},
 pages = {176--185},
 numpages = {10},
 url = {http://dx.doi.org/10.1109/RE.2006.17},
 doi = {10.1109/RE.2006.17},
 acmid = {1174006},
 publisher = {IEEE Computer Society},
 address = {Washington, DC, USA},
 keywords = {Systematic review, software engineering, elicitation techniques, empirical studies},
} 

Please help!

Answer 1

The line number in the error message is the line of the .bbl file that is generated by bibtex, it is not the line of the .bib file. Therefore the question quotes the wrong lines. The line in the error message contains:

pp. 225--236, 10.1007/978-0-387-68772-8_18. [Online].

Therefore I think the entry in the .bib file contains

doi = {10.1007/978-0-387-68772-8_18},

It seems the DOI numbers are not well supported. The prefix doi: is missing:

doi:10.1007/978-0-387-68772-8_18

Or as URL:

http://dx.doi.org/10.1007/978-0-387-68772-8_18

Also special characters like _ are not well supported. The _ causes the trouble. Make a minimal example (MWE) that shows, how the doi entries in the .bib file are handled in your document.

If there are no special macros that handle the doi numbers, then you can try \_ instead of _ in the .bib file.

Answer 2

\usepackage[strings]{underscore}

Answer 3

The problem is the underscore _ in a doi. It occurs in line 190 of the LaTeX file (or in the .bbl) not in the .bib file.

Search for 10.1007/978-0-387-68772-8_18 in your .bib file. You can use the url package and enclose the entry in \url{10.1007/978-0-387-68772-8_18} to avoid the error. Alternatively you can use a bibtex style that knows about dois.

Answer 4

Try using in the preamble \usepackage{url}. This should clear the problem.

Answer 5

Another solution could be to drop the whole "_18" as it says just "chapter 18". If you write "10.1007/978-0-387-68772-8" rather than "10.1007/978-0-387-68772-8_18" the reader will still be referred to the right book, but not to chapter 18 within it.

Answer 6

What Werner and Gonzalo said would indeed be very helpful. From the limited info given however, I guess LaTeX struggles with the _ in the line, since it normally sees that as a subscript indicator and only expects it in math mode.

A very short solution (and impossible to say if that works without taking a look at the offending code) is to escape the underscore ("_"), by placing a backslash before it.

Answer 7

To get rid of the underscore ("_"), you can use shortdoi.org and doi:10/djzjd6 instead of doi:10.1007/978-0-387-68772-8_18, which is also nice when your readers need to type the doi from a printed version of your thesis instead of being able to click at it in an electronic document.

Answer 8

Another future-proof answer, albeit rather tedious, is suggested here:

Change all occurrences of _ in the URL field of your .bib file to their html character code equivalent %5F

Answer 9

From a similar question, the answer that worked for me was adding

\usepackage{hyperref}
\usepackage[T1]{fontenc}

to the preamble. (Or \usepackage[hidelinks]{hyperref} to avoid the ugly boxes.)

Credit to Ulrike Fischer and CGFoX

Answer 10

The short way:

1. open "*.bib" file

2. Replace:

        "-" >>>> "\_"
        "&" >>>> "\&" (specially check in the links)
        "\" >>>> "\\" (specially check in the links)
   

3. Delete all temporary files: In Texmaker:

        Tools -> Clean
        Bibliography -> Clean
   

4. You are done! Very Important Note: You do not need any extra package, so do not use them, in order to prevent further problems.

Answer 11

If you are getting this issue when submitting to arXiv, one possible source of the problem may be that you are trying to use a .bib file as a .bbl.

While renaming the .bib to .bbl is pretty silly in retrospect, that's what I did (not understanding that they are different). And then I ran into these errors. You need to submit the .bbl that is generated when you compile on your machine (or, in my case, download the .bbl file produced by ShareLaTeX online). The format of the .bbl is different from the .bib and the references will not show up correctly or be cited correctly.

Answer 12

In my case there was a problem with the encoding. I used \usepackage[macintosh]{inputenc}.

I solved the problem by switching to \usepackage[utf8]{inputenc} but i also had to update the encoding of my files by using iconv.

Answer 13

If you are handling complex tex when using new packages might incur even more problems, I find a simple solution by replacing the underscore in the bib files' DOI link with \textunderscore, like this:

doi = {10.1007/978-3-319-45738-3\textunderscore9}

It should solve your issue in a second.