Schmalbach, B., M. Zenger, A. Nanette Tibubos, A. Borkenhagen, B. Strauss, and E. Brähler. “The Narcissistic Personality Inventory 8: Validation of a Brief Measure of Narcissistic Personality”. International Journal of Psychological Research, vol. 13, no. 2, Aug. 2020, pp. 68-77, doi:10.21500/20112084.4855.