Frances, A. ., Miele, G. ., Widiger, T. ., Pincus, H. ., Manning, D. ., & Davis, W. . The classification of panic disorders: from Freud to DSM-IV. Journal of Psychiatric Research, 27 Suppl 1, 3-10. https://doi.org/10.1016/0022-3956(93)90013-r (Original work published 1993)