Your header confused me about MLA vs. APA. In MLA, the author's name and the page number are included and right aligned, which you did. The new headers are APA, as they should be.

Here is the reference that goes on your list in ALPHABETICAL order.

National Institute of Health (2013). Stem cell information: Regenerative medicine. Retrieved from http://stemcells.nih.gov/info/Regenerative_Medicine/Pages/Default.aspx