The topic of your research paper often determines whether you'll need to format it using APA or MLA guidelines. Topics which are about literature, the studies of languages, literary criticism, and cultural studies are most often formatted using an MLA style. Topics which fall under social sciences (psychology, sociology, economics, linguistics), business, and nursing disciplines are most often formatted using an APA style. To begin, first consider how you could best classify your research topic and then choose the most appropriate style.
APA in-text citations should include the author's last name, the year of publication, and the page number (which is preceded by p. for a single page and pp. for multiple pages). It looks like this:
Researchers found that students preferred to read texts with complex characters (Smith, 2020, p. 25).
MLA in-text citations do not require the year of publication and also do not include the p. before the page number. The author and page number are not separated by commas. The same example would look like this using MLA:
Researchers found that students preferred to read texts with complex characters (Smith 25).
The rules for formatting an interview using APA would fall under "personal communication." An in-text citation would be formatted like this:
(E. Smith, personal communication, October 12, 2021).