Why Same-Author Same-Year Citations Need Letters
When you cite two or more works by the same author published in the same year, APA 7th edition requires you to distinguish them with lowercase letters attached to the year: (Hassan, 2020a) and (Hassan, 2020b). Without these letters, a reader cannot tell which of the two works a given in-text citation points to, and the reference list becomes ambiguous. This situation is common in Malaysian theses that draw heavily on a single prolific local researcher, or on a government agency that released several reports in one year. Getting the suffix letters right is a small mechanical task, but inconsistency between the text and the reference list is exactly the kind of error a careful examiner flags.
Assigning a and b Letters Correctly
The letters are not assigned by the order in which you cite the works in your thesis. APA assigns them alphabetically by the title of the work, ignoring “A”, “An”, and “The” at the start. So if Hassan published “Assessment practices” and “Learning outcomes” in 2020, “Assessment practices” becomes 2020a and “Learning outcomes” becomes 2020b, regardless of which you mention first in your writing. Once assigned in the reference list, the letters travel with the year everywhere the work appears in the text. If a work genuinely has no date, the same logic applies using n.d.-a and n.d.-b. Assign the letters only after your reference list is complete, because adding a new source later can shift the alphabetical order and change which work is a and which is b.
Matching In-Text Citations to the Reference List
The most frequent failure is a mismatch: the text cites (Hassan, 2020b) but the reference list shows only Hassan 2020a, or the two reference entries lack letters entirely. Before submission, list every author who appears more than once for the same year and check each one in both places. A quick method is to search your document for each such author’s surname and confirm that every instance carries the correct letter and that both lettered entries exist in the reference list. If you cite both works together in one parenthesis, combine them as (Hassan, 2020a, 2020b), and in the reference list the two entries appear as separate lines, each beginning with the author and the lettered year, ordered a before b. Note that the lettering applies only when the year is identical; two works by the same author in different years need no letters at all, since the year alone already distinguishes them. Checking same-author same-year citations systematically before you submit removes a quiet but recurring source of referencing errors in Malaysian postgraduate theses.
