COLIN BLAKEMORE and SHELIA JENNETT. "weightlessness." The Oxford Companion to the Body. Oxford University Press. 2001. Encyclopedia.com. 9 Jul. 2009 <http://www.encyclopedia.com>.
COLIN BLAKEMORE and SHELIA JENNETT. "weightlessness." The Oxford Companion to the Body. Oxford University Press. 2001. Encyclopedia.com. (July 9, 2009). http://www.encyclopedia.com/doc/1O128-weightlessness.html
COLIN BLAKEMORE and SHELIA JENNETT. "weightlessness." The Oxford Companion to the Body. Oxford University Press. 2001. Retrieved July 09, 2009 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-weightlessness.html