If the sources have different years, list each beginning with the earliest year:
Example: Porter, K. (2001). I love artisanal cheeses. Aberdeen, SD: Cheese Lovers Publishing. Porter, K. (2008). How I added a second mortgage to buy more cheese. Aberdeen, SD: Cheese Lovers Publishing.
If the sources have the same year, alphabetize by title. Put a suffix by the year to indicate which is first.
Example: Mellen, H. (2010a). The role of religion in The Canterbury Tales. Journal of British Literature. 15, 45-58. Mellen, H. (2010b). Was the Pardoner the voice of god?. Journal of British Literature. 16, 78-96.
