I am working on a paper in which I cite two resources from an online reference work with no author:
Ransomware. (2016). Malware Protection Center. Retrieved from http://www.microsoft.com/security/portal/mmpc/shared/ransomware.aspx
Ransomware. (2016). TrendMicro. Retrieved from http://www.trendmicro.com/vinfo/us/security/definition/ransomware/#logo
Unfortunately, these two works have identical in-text citations: "('Ransomware,' 2016)." The only material I can find on situations like this is when the authors are the same, and the remedy is to append the letters "a" and "b" to the date, like (2016a). These works, however, do not have the same author, so I do not think this fix can be used. How should I differentiate between these two citations?