Search and download PDF files for free
搜索功能使用google,需要科学上网
a volunteer-driven effort to produce a collection of high quality, carefully formatted, accessible, open source, and free public domain ebooks that meet or exceed the quality of commercially produced ebooks.
IT电子书
free computer science ebooks
备用域名:wdl.org
需科学,Internet Archive的National Emergency Library (国家紧急图书馆)