- Geekzone: Microsoft announces expansion of Shared Source Initiative. [2011-01-21]. （原始内容存档于2012-03-12）.
- Open vs. Closed Source Software. scienceinafrica.co.za. January 2004 [2011-01-21]. （原始内容存档于2011-02-07）.
- ZDNet Definition for: Closed Source. ZDNet. [2011-01-21]. （原始内容存档于2008-07-31）.
Proprietary software owned by one organization. The term is typically used only in discussions that contrast open source software with proprietary software