https://vimeo.com/41027679
https://vimeo.com/41381741
https://try.github.io/levels/1/challenges/1
http://blog.atena.pl/wprowadzenie-do-mavena
https://www.youtube.com/watch?v=al7bRZzz4oU&list=PL92E89440B7BFD0F6&index=1
https://www.youtube.com/watch?v=KlIM897RGwc&index=2&list=PL92E89440B7BFD0F6
https://www.youtube.com/watch?v=IYRYbPR5Gek&list=PL92E89440B7BFD0F6&index=4
https://www.youtube.com/watch?v=IRKu8_l5YiQ&list=PL92E89440B7BFD0F6&index=5