There are no examples of referencing a letter to the editor in the APA Publication Manual or in the APA Style Blog, however, there is mention of them. The Library suggest following the format below:
Writer/author. (Year, Month date). Title [Letter to the editor]. Title of newspaper, page number. Retrieval statement
Example with author:
McHugh, J. (1993, June 10). It’s past time to make a change [Letter to the editor]. The Canberra Times, 12. Retrieved from http://trove.nla.gov.au/newspaper/article/127238555
Example no author:
ANZAC Day Observance [Letter to the editor]. (1944, April 26). The Mercury, 3. Retrieved from http://trove.nla.gov.au/newspaper/article/26023751
If the letter you are referencing is from a print newspaper (i.e. not sourced online), omit the retrieval statement.
