I find some useful small searching technique today.
I list them below as a memoir:
1. use site: xxx.com to search what you want in xxx.com.
2. use filetype:pdf to search pdf file.
3. use intitle: to search those website which has key words in their titles.
4. use google
a useful searching website: http://search.chongbuluo.com/
原文：http://www.cnblogs.com/LiXinze/p/7633088.html