natbib - 在单独的 tex 文件中引用

Question

我在博士论文的引用方面遇到了麻烦。我已经查看了其他帖子，但找不到任何解决方案……如果有人能帮助我，我会非常高兴。

我希望我的论文末尾有一个参考书目，由单独文件中的几个章节组成。

编辑：

这是一个最小的工作示例：

\RequirePackage{filecontents}
\begin{filecontents*}{test1.tex}
\chapter{Chapter One}
Text1 \cite{nishikawa_unique_2006} 
\end{filecontents*}
\begin{filecontents*}{test2.tex}
\chapter{Chapter Two}
Text2 \cite{struchholz_functional_2009}
\end{filecontents*}
\begin{filecontents*}{test3.tex}
\chapter{Chapter Three}
Text3 \cite{nishikawa_unique_2006} \cite{struchholz_functional_2009}
\end{filecontents*}

\documentclass[a4paper, liststotoc, bibtotoc, 12pt, numbers=noenddot, twoside]{book}
\usepackage[authoryear,comma,nonamebreak,round,sort&compress]{natbib}
\bibliographystyle{plainnat}

\begin{document}
\include{test1}
\include{test2}
\include{test3}
\bibliography{literature}
\end{document}

.bib 文件包含

@article{nishikawa_unique_2006,
    title = {A unique mechanism for the processive movement of single-headed myosin-{IX}},
    volume = {343},
    abstract = {XXX},
    language = {en},
    number = {4},
    urldate = {2020-03-23},
    journal = {Biochemical and Biophysical Research Communications},
    author = {Nishikawa, Masatoshi and Nishikawa, So and Inoue, Akira and Iwane, Atsuko Hikikoshi and Yanagida, Toshio and Ikebe, Mitsuo},
    month = may,
    year = {2006},
    pages = {1159--1164},
}

@article{struchholz_functional_2009,
    title = {Functional {Role} of the {Extended} {Loop} 2 in the {Myosin} 9b {Head} for {Binding} {F}-actin},
    volume = {284},
    language = {en},
    number = {6},
    urldate = {2020-03-23},
    journal = {Journal of Biological Chemistry},
    author = {Struchholz, Sandra and Elfrink, Kerstin and Pieper, Uwe and Kalhammer, Georg and Honnert, Ulrike and Grützner, Anika and Linke, Wolfgang A. and Liao, Wanqin and Bähler, Martin},
    month = feb,
    year = {2009},
    pages = {3663--3671},
}

这个例子可以工作，但如果包含我写的章节（80 页），它就不起作用，我只得到?? 而不是引用.... 我的外部文件不知何故有问题，但它只包含文本和引用