@book{Kelty_2008,
 author = {Kelty, Christopher},
 year = {2008},
 title = {Two bits: The cultural significance of free software},
 url = {http://twobits.net/pub/Kelty-TwoBits.pdf},
 address = {Duham/London},
 urldate = {03.12.2015},
 publisher = {{Duke University Press}}
}