From the Dissertation Manual:
Most literature reviews contain, at a minimum, 30 references from recent peer-reviewed research articles (i.e., primary sources), as well as additional resources (e.g., books, dissertations, scholarly research articles, etc.). Exhaustive literature reviews usually exceed 25-30 pages in length. To meet this benchmark, the Proposal Development must receive full committee approval. Students are highly encouraged to schedule one-on-one appointments with the NSU Library to conduct a comprehensive search for relevant and recently published articles. Citations in the text should be included in a Reference list and adhere to correct APA style (Note: References not cited in the text should be excluded from the Reference list.