Citation is a tricky area, since various writing styles require different formats. The most important part of citation is to figure out which style you are writing in, and then adhere strictly to its format. These citations are MLA format; they would look slightly different in APA or other formats. There are many online resources available to help with citations; check the OWL at Purdue and the Citation Machine for two options.
To properly cite resources on critical thinking, first the resource itself must be found and its information recorded. One great tool is available right here on eNotes: check the top of any eNotes reference or study guide page to find a handy "Cite" button, which pops up the proper citation for any eNotes resource. For example, the citation for the eNotes Wikipedia page on "Critical Thinking" is cited as follows:
"Critical thinking." Wikipedia, The Free Encyclopedia.
Wikimedia Foundation, Inc. 2004. 19 July 2012
Notice that "eNotes" is not listed, because the page is a mirror of another page. Original content pages on eNotes will cite directly from eNotes, with a similar format.
Another important fact is about the format of the citation itself; the second and following lines are indented, usually five spaces or one Tab, depending on software. All style guides will show how the indentations should be formatted.
Another resource for critical thinking is criticalthinking.net; a citation for the "Definition" page of that website would look like this:
Ennis, R. H.. "A SUPER-STREAMLINED CONCEPTION OF
CRITICAL THINKING."Critical thinking. N.p., 2011.
Web. 19 Jul 2012.
You can see how the last edited date is listed, and then the date accessed; this is useful in case the information listed on the page changes.
For print works, the information must be gathered from the copyright page and typed manually. A citation for the book Teaching Critical Thinking: Practical Wisdom, by Bell Hooks, would look like this:
Hooks, Bell. Teaching Critical Thinking. 1st. New York:
Routledge, 2010. Print.
In this case, the "date accessed/read" is not necessary, because that edition of the book is not subject to change. Many books are available for preview on Google Books, making their copyright information easy to find. Check a style guide for more in-depth information, and good luck!