APA (7th ed.) Citation

Webb, E. J. (2000). Unobtrusive measures (Rev. ed.). Sage.

Chicago Style (17th ed.) Citation

Webb, Eugene J. Unobtrusive Measures. Rev. ed. Thousand Oaks, Calif: Sage, 2000.

MLA (9th ed.) Citation

Webb, Eugene J. Unobtrusive Measures. Rev. ed. Sage, 2000.