我的 BibTeX 在某个引用之后就无法正常工作了。在这个引用之后，每个引用都是一个问号。
@book{digital,
author = {J.G.Proakis},
title = {Digital Transmission},
year = {2001},
publisher = {McGraw-Hill},
}
而且 LaTeX 也会出现错误信息。
*Command \c@lofdepth already defined.
You requested the `dvips' driver but I think that(crop) the `pdftex' driver works better in the current(crop) context. You can force me to respect your decision(crop) by adding an exclamation point as in [dvips!].
Font shape `T1/cmss/m/n' in size <40> not available(Font) size <35.83> substituted on input line 52. Font shape `T1/cmss/m/n' in size <40> not available(Font) size <35.83> substituted
Citation `niklas' on page 9 undefined on input line 310. Citation `niklas' on page 9 undefined
There were undefined citations.
Size substitutions with differences(Font) up to 4.17pt have occurred.*
这些错误让我抓狂。当 BibTeX 正常工作时，LaTeX 编译时不会出现这些错误。
这是我的代码
\documentclass[11pt,twoside]{eitExjobb}
\usepackage[T1]{fontenc}
\usepackage{color}
\usepackage{graphpap}
\usepackage{subfigure}
\unitlength=1mm
\begin{document}
%%% Title page
\Title{A Test of \texttt{Exjobb.cls}}
\Author{Stefan Höst\\\texttt{stefan}}
\Date{\today}
\Advisor{Stefan Höst}
%%\Company{Company\\Address}
\MakeTitlePage
%%%%% Page numbering for front pages
\frontmatter
%%%%% Abstract
\chapter*{Abstract}
%% ToC
\tableofcontents
%\cleardoublepage
\listoffigures
\listoftables
\cleardoublepage
%%%%% Page numbering for the main thesis
\mainmatter
%%%%%
\chapter*{Introduction}
\cite{9999}
\cite{niklas}
\cite{Boyd:2004:CO:993483}
%%%%%%%%%%%%%%%%%%%
\bibliographystyle{unsrt}
\bibliography{reference}
\end{document}
在代码中我引用了三个参考文献。只有最后一个有效。我的reference.bib是。
@ARTICLE{372015,
author={Zou, W.Y. and Yiyan Wu},
journal={Broadcasting, IEEE Transactions on}, title={COFDM: an overview},
year={1995},
month={mar},
volume={41},
number={1},
pages={1 -8},
keywords={8-VSB;ACATS;ATV channel model;Advisory Committee on Advanced Television Service;COFDM;Europe;FCC;OFDM;QAM;USA;channel coding;coded OFDM;development;digital audio broadcasting;digital modulation;digital television broadcasting;history;imperfect channel conditions;orthogonal frequency division multiplexing;performance;research;terrestrial HDTV broadcasting;channel coding;digital television;encoding;frequency division multiplexing;high definition television;quadrature amplitude modulation;reviews;television broadcasting;},
doi={10.1109/11.372015},
ISSN={0018-9316},}
@ARTICLE{54342,
author={Bingham, J.A.C.},
journal={Communications Magazine, IEEE}, title={Multicarrier modulation for data transmission: an idea whose time has come},
year={1990},
month={may },
volume={28},
number={5},
pages={5 -14},
keywords={channel impairments;coding;data transmission;duplex operation;frequency division multiplexing;general switched telephone network;multicarrier modulation;undistorted channel;data communication systems;encoding;frequency division multiplexing;modulation;},
doi={10.1109/35.54342},
ISSN={0163-6804},}
@ARTICLE{713060,
author={Merchan, S. and Armada, A.G. and Garcia, J.L.},
journal={Broadcasting, IEEE Transactions on}, title={OFDM performance in amplifier nonlinearity},
year={1998},
month={mar},
volume={44},
number={1},
pages={106 -114},
keywords={16QAM;ACTS project;BER degradation;Europe;OFDM performance;OFDM signals;QPSK;RACE project;Signal Processing Worksystem simulator;additive Gaussian noise;amplifier nonlinearity;amplitude clipping;amplitude limiting;bandwidth;bit error rate;digital TV broadcasting;impulsive noise;multipath effects;nonlinear distortion;optimized output power back off;orthogonal frequency division multiplexing;power amplifier efficiency;Gaussian noise;coding errors;digital television;error statistics;frequency division multiplexing;multipath channels;quadrature amplitude modulation;quadrature phase shift keying;radiofrequency amplifiers;television broadcasting;},
doi={10.1109/11.713060},
ISSN={0018-9316},}
答案1
问题不在于 bib 文件。正如 mico 所说，缺少一个逗号：如果您查看日志文件，您会看到报告。但这不是问题。
我认为，问题在于您正在加载的自定义类加载了tocloft，而您加载了subfigure。碰巧存在冲突，因为两者都试图定义相同的计数器。这通常没有问题，因为 tocloft 会检查是否正在使用 subfigure：但反之则不然，而且由于您的类首先加载 tocloft，所以出错了。我认为解决方案是编辑您的类文件以在 tocloft 之前加载 subfigure，并使用选项加载 tocloft subfigure。
您之所以看到问号而不是引文，是因为您被错误耽误了，而且只运行了一次 latex，所以引文标记并没有自行解决。事实上，如果您不顾错误继续操作（这不是一个好主意），您就会得到引文：这个问题与您的 bibtex 无关。
我希望这样说不会太过苛刻，这确实证明了阅读日志和发布 MWE 的重要性。