|Citizendium - a community developing a quality comprehensive compendium of knowledge, online and free. Click here to join and contribute—free
|CZ thanks JULY 2014 donors; special to Darren Duncan. AUGUST 2014 donations open; need minimum total $100. Let's exceed that. Donate here. Donating gifts yourself and CZ. -- Thanks to July content contributors. --
From Citizendium, the Citizens' Compendium
*The number in parenthesis () is the uncertainty. This data was taken from the Physical Reference Data web site of NIST on December 2, 2007.