Multiple works by the same author, same year
Sources written by the same author in the same year are distinguished by adding a, b, c, etc. after the year.
Example:
(Lohndal, 2015a, 2015c) … (Lohndal, 2015b)
In the bibliography, the sources should be listed in alphabetical order based on the title (here G, R and S). Ignore any indefinite and definite articles when alphabetizing. It is the sorting in the bibliography that controls the order of a, b, c.
Example:
Lohndal, T. (2015a). Grammatikk og struktur. Norsklæreren, 39(3), 74–75.
Lohndal, T. (2015b). Review of «Syntax of Substance». Linguistic Analysis, 39, 431–435.
Lohndal, T. (2015c). Språk er i hjernen. Språknytt, 43(2), 22–24.
If you have exact publication dates, put the dates in chronological order before alphabetizing the titles.
If the sources have several authors, but the same first author published in the same year, you must add as many author names as you need to distinguish the references.
If the sources are missing publication year, there should be a hyphen before the letter: (n.d.-a), (n.d.-b), etc.