Sharelatex 无法识别 bib 文件的相对路径

Question

我在使用 sharelatex 尝试使用与主 tex 文件位于不同目录中的 bib 文件列表时遇到问题。我的文件结构是：

- tex_folder
    * tex_file
- bib_folder
    * bib_file1
    * bib_file2

这是 tex_file

    \documentclass{article}
    \usepackage[utf8]{inputenc}

    \title{test}
    \author{ }
    \date{October 2016}

    \begin{document}

    \maketitle

    \section{Introduction}
    testing my bibliography \cite{ref1}

   \bibliographystyle{plain}
   \bibliography{../bib_folder/bib_file1, ../bib_folder/bib_file2}

    \end{document}

以及这个bib_file1.bib：

    @ARTICLE{ref1,
    author = {author_list},
    title = {nice_title},
    journal = {J. of journal},
    year = {2010}
    }

我收到以下错误：

    You have cited something which is not included in your bibliography. Make sure that the citation (\cite{...}) has a corresponding key in your bibliography, and that both are spelled the same way.


    BibTeX I couldn't open database file ../bib_folder/bib_file1}

提前致谢！