If there is not a separate author listed, the web page sponsor can be considered to be the page's author, unless otherwise specified.
Centers for Disease Control and Prevention. (n.d.). What is health literacy? https://www.cdc.gov/healthliteracy/learn/index.html
(Centers for Disease Control and Prevention, n.d.)
Freitas, N. (2015, January 6). People around the world are voluntarily submitting to China’s Great Firewall. Why? Slate. http://www.slate.com/blogs/future_tense/2015/01/06/
Nafees, Q., Yilong, Y., Andras, N., Zhiming, L., & Janos, S. (2014, November 19). Anonymously analyzing clinical data sets. Cornell University. http://arxiv.org/abs/1501.05916
(Nafees et al., 2014)
See Publication Manual, 10.16.