I will record some useful links which inspired or are inspiring me.
I thank every author for his or her valuable information!
Deal.ii tutorials and other useful techniques:
Author: Qi xinbo
Hexo personal website detailed tutorials:
Author: Wei Yang
https://godweiyang.com
Many adviceds for begining programmers:
Author: 水寒
https://dp2px.com
UbuntuHandbook
Author: Ji m
http://ubuntuhandbook.org/index.php/about/