If you're writing a paper using APA style -- based on the style guidelines in the "Publication Manual of the American Psychological Association" -- it's important that you obtain a copy of the latest edition of the book, because you will need to refer to it often. APA style is a common requirement for papers written in the social sciences. When you are using a textbook as a source in your References list, you cite it the same way you would cite any other book.
Type the first author's name. You type her last name first, followed by a comma, followed by her initials. It looks like this: Koslowski, M. J.
Type other authors' names -- if there are other authors -- similarly. You separate each name using a comma, and you use an ampersand instead of the word "and." It looks like this: Koslowski, M. J., & Butterfield, E. L.
Follow the name or names with the year your textbook was published in parentheses, followed by a period: Koslowski, M. J., & Butterfield, E. L. (2013).
Add the title of the textbook next, followed by a period. The title should appear in italics, and surprisingly, in APA style only the first word in the book title is capitalized: Koslowski, M. J., & Butterfield, E. L. (2013). Cognitive psychology in the classroom.
Type the location and the publisher next. You type the city, a comma, and the state, using the two-letter postal abbreviation for the state. You follow that with a colon. Then you type the name of the publisher, followed by a period. The final citation would look like this: Koslowski, M. J., & Butterfield, E. L. (2013). Cognitive psychology in the classroom. Boston, MA: Bedford/St. Martin's.