Bibtex natbib：参考书目中的工作文件和DOI

我在参考书目方面有两个问题。首先，当我引用一些工作文件时，不显示工作文件的完整信息，只显示以下信息

施瓦茨，S.L.（2008）。系统性风险

但是，有关发布者、工作论文系列和url的信息可以在bib文件中找到。 其次，参考文献的DOI和URL不显示在参考书目中。 下面给出了一个简单的工作示例：

   \documentclass[12pt,twoside,openany]{book}
   \usepackage{authblk}
   \usepackage{titlesec}
   \usepackage[T1]{fontenc}
   \usepackage{times}
   \usepackage[latin9]{inputenc}
   \usepackage[english]{babel}
   \usepackage[round,nonamebreak]{natbib}

   \begin{document}
    \author{Ahmed Arif}
    \title{A Book}

   \chapter{Introduction}
   This is introduction chapter \citep{Schwarcz2008}. The literature is        cited here \citet{Cebenoyan2004}.

   \bibliographystyle{apa}
   \bibliography{library}
   \end{document}

bib文件中可用的条目如下所示。bib文件是从mendley处获得的

    @article{Cebenoyan2004,
    author = {Cebenoyan, A.Sinan and Strahan, Philip E},
    doi = {10.1016/S0378-4266(02)00391-6},
    file = {:C$\backslash$:/Users/Ahmed Arif/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Cebenoyan, Strahan - 2004 - Risk management, capital structure and lending at banks.pdf:pdf},
    issn = {03784266},
    journal = {Journal of Banking {\&} Finance},
    keywords = {7 december 2001,at the x international,bank risk management,banking and finance held,in rome on 5,loan sales,this paper was presented,tor vergata conference on},
    month = {jan},
    number = {1},
    pages = {19--43},
    title = {{Risk management, capital structure and lending at banks}},
    url = {http://linkinghub.elsevier.com/retrieve/pii/S0378426602003916},
    volume = {28},
    year = {2004}
    }
    @unpublished{Schwarcz2008,
    address = {Durham},
    author = {Schwarcz, Steven L.},
    file = {:C$\backslash$:/Users/Ahmed Arif/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Schwarcz - 2008 - Systemic Risk.pdf:pdf},
    institution = {Duke Law School},
    pages = {193--249},
    series = {Research Paper Series},
    title = {{Systemic Risk}},
    url = {http://papers.ssrn.com/sol3/papers.cfm?abstract{\_}id=1008326},
    year = {2008}
    }