乳胶参考编号混合问题

Question

我只是在编写一个普通文件，当我尝试使用引用时，顺序就混乱了。我不知道为什么会发生这种情况。它就像 2-3 然后是 1。

\documentclass[12pt]{article}
\usepackage{amsmath} 
\numberwithin{equation}{subsection}
\usepackage{graphicx}
\graphicspath{ {./Images/} }

\begin{document}

\section{Expansion of the Universe}
\subsection{Einstein's Static World Model}

 This universe model allows us to set $a = 1$ and $\dot{a}=\ddot{a}=0$ \cite{Roos}.
 But Einstein did not notice that the static universe solution is at a point of unstable equilibrium  \cite{Barbara}.

 \subsection{The Expansion of the Universe and Hubble Law}
 he was able to measure the distance of the nebulas. \cite{Hubble}

\bibliography{References}
\bibliographystyle{plain}

\end{document}

我是这样引用的。我没有引用图表。但我有小节，也许这就是它发生的原因？这是我的 bib 文件。

@inbook{Roos,
author    = {Matts Roos}, 
title     = {Introduction to Cosmology},
chapter      = 5,
pages        = {84},
publisher = { Wiley},
year      = 2015,
edition   = 4,
}



@inbook{Barbara,
author    = {Barbara Ryden}, 
title     = {Introduction to Cosmology},
chapter      = 4,
pages        = {87-89},
publisher = { Cambridge University Press},
year      = 2017,
edition   = 2,
}


@article {Hubble,
    author = {Hubble, Edwin},
    title = {A relation between distance and radial velocity among extra-galactic nebulae},
    volume = {15},
    number = {3},
    pages = {168--173},
    year = {1929},
    doi = {10.1073/pnas.15.3.168},
    publisher = {National Academy of Sciences},
    issn = {0027-8424},
    URL = {https://www.pnas.org/content/15/3/168},
    eprint = {https://www.pnas.org/content/15/3/168.full.pdf},
    journal = {Proceedings of the National Academy of Sciences}
}