More than one source with same author(s) and date

It sometimes happens that you need to use more than one source that has the same authors and the same year.  What are you going to do about that?  Read on to get the 411 on how to handle that in APA 6th edition style like a boss. 

Here’s the example sources (by the way, these sources are completely fictitious):

Majik, K, A., & Sly, T. (2015). Growth of catnip in mountainous regions of Kentucky. American Journal of Common Plants, 10(2), 445-461.

Majik, K, A., & Sly, T. (2015). Napeta cateria potency and its negative influence on American house cats. American Journal of Cats, 8(14), 73-101.

Majik, K, A., & Sly, T. (2015). Saving our cats: Creating catnip addiction clinics in large American cities. American Journal of Amazing Stuff, 5(10), 13-26.

As a responsible researcher, you will want your readers to be able to distinguish among the sources that have the same authors.  If the works were published in different years, there would be no problem with the citations.  Therein lies the solution – make the dates distinguishable. 

Change the dates by adding a lower-case letter after each date.  Like this:

Majik, K, A., & Sly, T. (2015a). Growth of catnip in mountainous regions of Kentucky. American Journal of Common Plants, 10(2), 445-461.

Majik, K, A., & Sly, T. (2015b). Napeta cateria potency and its negative influence on American house cats. American Journal of Cats, 8(14), 73-101.

Majik, K, A., & Sly, T. (2015c). Saving our cats: Creating catnip addiction clinics in large American cities. International Journal of Amazing Stuff, 5(10), 13-26.

When writing citations for your sources, use the date with the lowercase letter.  That way, the reader can be certain of the source.   To give some examples (and again, this information is completely invented for convenience):

According to Majik and Sly (2015b), cats become more impulsive when they have indulged in catnip.

Eastern Kentucky is well known for large fields of potent catnip, and an unusually large population of feral cats (Majik & Sly, 2015a).

Majik and Sly (2015c) asserted that treating cats for catnip addiction is only effective when the cat realizes it has a problem with catnip. 

The next time you have the situation of multiple sources with the same date, it should be a nonevent.