It depends on the style you’re using. Here are a few examples:
"Global Climate Change: Evidence." NASA Global Climate Change and Global Warming: Vital Signs of the Planet. Jet Propulsion Laboratory / National Aeronautics and Space Administration, 15 June 2008. Web. 14 Jan. 2015. <http://climate.nasa.gov/evidence/>.
“Webpage Name.” Website Name. Publisher, Publication date. Source type. Date user accessed the webpage. <URL>.
"Global Climate Change: Evidence." NASA Global Climate Change and Global Warming: Vital Signs of the Planet. June 15, 2008. Accessed January 14, 2015. http://climate.nasa.gov/evidence/.
“Webpage Name.” Website Name. Publication date. Date user accessed the webpage. URL.
Global Climate Change: Evidence. (2008, June 15). Retrieved January 14, 2015, from http://climate.nasa.gov/evidence/
Webpage Name. (Publication date). Retrieved [Date user accessed the webpage], from [URL]
In general, include as much information as possible in your citations. For example, if one of our pieces is dated to “November 2010” (i.e., without a day), then you would need to write it as “Nov. 2010” in MLA format, “November 2010” in Chicago style and so on.
Citationgenerator.com is also a useful source for creating bibliographies.