All the websites below have a plenty of books and papers for free reading & downloading.
The National Academies Press, free reading and downloading in PDF, account needed for downloading.
Australian National University Open Research Library, all materials come from ANU, fill a form to request the PDF copy.
The University of Adelaide > Library > eBooks, free reading and downloading in HTML, epub, and Kindle.
Curtin University Library, free reading and downloading in PDF.
University of Queensland, part free.
Project Gutenberg, the greatest one, no more explianation.
The New Zealand Digital Library, free reading online.
Cornell University Library, free downloading in PDF.
你好！
我在opencart 中尝试使用你写的CDN插件，在后台上传成功后，确实生成了system/library/response.php
但是在执行输出的时候，所有图片、脚本、css网址均不能替换！还是用源站的资源，没有替换成缓存的资源地址！ 求教，怎么处理，看起来是ocmod没执行成功！
这个很难讲是什么原因，如果 ocmod 的替换的 response.php 已经生成，那么就需要检查一下权限。还有可以手工添加代码到 response.php 里，比如 die(‘here’); 然后看看是不是有调用到这个文件。