Paper  bibtex   

@misc{ 37signals_llc_basecamp:_????,
  title = {Basecamp: Integrations, Apps, and Add-ons to get more out of Basecamp.},
  copyright = {37signals, {LLC}},
  url = {http://basecamp.com/extras},
  language = {Inglés},
  urldate = {2013-02-21},
  journal = {Basecamp: Integrations},
  author = {{37signals, {LLC}}}
}