Page is a not externally linkable
-- Google SEO News and Discussion
---- New look "Google Knowledge" replaces results with content
rowtc2 - 12:04 am on Dec 21, 2013 (gmt 0)Thread source:: http://www.webmasterworld.com/google/4632162.htm
Probably they have agreements and make some sponsorships to Wikipedia, i do not think they are not covered by law.
Donate and contribute to Wiki and Google will benefit from ads using their(your) contribution.
Brought to you by WebmasterWorld: http://www.webmasterworld.com