Miller, M. W., Kaloupek, D. G., Dillon, A. L., & Keane, T. M. (2004). Externalizing and internalizing subtypes of combat-related PTSD: a replication and extension using the PSY-5 scales. Journal of Abnormal Psychology, 113(4), 636–645. https://doi.org/10.1037/0021-843X.113.4.636