useful link

http://stackoverflow.com/questions/927358/how-to-undo-last-commits-in-git
http://askubuntu.com/questions/97936/terminal-command-to-set-audio-volume
http://utahcon.com/i3-config-and-xev/
http://www.ninjaducks.in/hacking/gnome-3-to-i-3/
http://blog.tunnelshade.in/2014/05/making-i3-beautiful.html
http://stackoverflow.com/questions/4241211/how-do-i-convert-an-activerecord-result-array-to-a-normal-array
http://stackoverflow.com/questions/942543/operation-on-every-pair-of-element-in-a-list
http://askubuntu.com/questions/40126/how-to-copy-paste-a-table-from-libreoffice-calc-to-libreoffice-writer
https://ask.libreoffice.org/en/question/21286/change-page-numbering-in-the-content-field/
http://imron02.blogspot.co.id/2012/04/penomoran-halaman-pada-libreoffice.html
http://bektimaryuni.blogspot.co.id/2012/12/membuat-daftar-isi-daftar-tabel-daftar.html
http://riyan123qwe.blogspot.co.id/2012/03/cara-membuat-daftar-gambar-otomatis.html?m=1
http://askubuntu.com/questions/40126/how-to-copy-paste-a-table-from-libreoffice-calc-to-libreoffice-writer

http://milq.github.io/install-latex-ubuntu-debian/
http://stackoverflow.com/questions/1017055/get-started-with-latex-on-linux

http://www.electronics.oulu.fi/latex/examples/example_3/

http://repository.usu.ac.id/bitstream/123456789/16465/4/Chapter%20II.pdf --> paper untuk search dokumen
http://stevenloria.com/finding-important-words-in-a-document-using-tf-idf/

https://docs.python.org/2/library/math.html#math.log10