Cita APA (7th ed.)

Katz, W. A. (2003). Digital reference services. Haworth Information Press.

Cita Chicago (17th ed.)

Katz, William A. Digital Reference Services. Binghamton, N.Y: Haworth Information Press, 2003.

Cita MLA (9th ed.)

Katz, William A. Digital Reference Services. Haworth Information Press, 2003.