does a free culture look like?. Students of Free culture. [2009-10-24]. （原始内容存档于2012-09-19）.  What is free culture?. Students of Free culture. [2009-10-24]

Gray, Peter. Free to Learn: Why Unleashing the Instinct to Play Will Make Our Children Happier, More Self-Reliant, and Better Students for Life. Basic

無毒世界基金會（Foundation for a Drug-Free World），也稱無毒世界協會（Drug-Free World Organization）是由山達基教會於2006年設立，總部位於美國加州洛杉磯的一個反毒宣傳組織。山達基教會稱該基金會作爲山達基人在社會上做好事的例證之一。同其他

students of folk-stories." Kindle 3G Wireless Reading Device. 2010-08-04. （原始内容存档于2010-08-04）. Wireless Access to Wikipedia Kindle also includes free

card）的主题。而在此前，色情印刷品还局限在雕版、木刻和线版的插画上。 Ashcroft v. The Free Speech Coalition. CaseBrief for Law Students. Casebriefs LLC. [2020-07-03]. （原始内容存档于2020-11-29）