用到这个包：
\usepackage{url}
然后在你的.bib文件里写上
@Misc{timmurphy.org,howpublished = {\url{http://timmurphy.org/2009/07/22/line-spacing-in-latex-documents/}},note = {Accessed April 4, 2010},title = {Line Spacing in LaTeX documents},author = {Murphy, Timothy I}}
转载自：http://blog.csdn.net/techfield/article/details/19933589