A published doctoral dissertation usually resides in a database, such as the Networked Digital Library of Theses and Dissertations (NDLTD) or the ProQuest Dissertations & Theses database. As such, the APA reference for published dissertations should include the database where it can be found and the accession or order number. Also the words "doctoral dissertation" are included directly after the title, to define the exact nature of the resource.
In-text citations for published dissertations follow the standard "Author, Year" format.
If you use a parenthetical citation, it will look like this:
A recent study has shown that the effectiveness of graphic novels used as reading-comprehension tools lessens with low-functioning readers (Lamanno, 2007).
Alternatively, you can use the author's name in a signal phrase, like this:
Lamanno's (2007) study shows that the effectiveness of graphic novels with regard to reading comprehension lessens with low-functioning readers.
Here is the generic APA format for published dissertations:
Lastname, F. N. (Year). Title of dissertation (in italics). (Doctoral dissertation). Retrieved from Name of database. (Accession or Order Number)
Here is an example of a published dissertation reference:
Lamanno, A. A. (2007). Exploring the use of graphic novels in the classroom: Does exposure to non-traditional texts increase the reading comprehension skills and motivation of low-functioning adolescent readers? (in italics) (Doctoral dissertation). Retrieved from ProQuest Dissertations & Theses database. (3284960)