Ambach, E; Parson, W; Brezinka, C (2000). "Superfecundation and dual paternity in a twin pregnancy ending with placental abruption". Journal of Forensic Sciences. 45 (1): 181–3. doi:10.1520/JFS14656J. PMID10641935.
McNamara, Helen C.; Kane, Stefan C.; Craig, Jeffrey M.; Short, Roger V.; Umstad, Mark P. (2016). "A review of the mechanisms and evidence for typical and atypical twinning". American Journal of Obstetrics and Gynecology. 214 (2): 172–91. doi:10.1016/j.ajog.2015.10.930. PMID26548710.
Ambach, E; Parson, W; Brezinka, C (2000). "Superfecundation and dual paternity in a twin pregnancy ending with placental abruption". Journal of Forensic Sciences. 45 (1): 181–3. doi:10.1520/JFS14656J. PMID10641935.
McNamara, Helen C.; Kane, Stefan C.; Craig, Jeffrey M.; Short, Roger V.; Umstad, Mark P. (2016). "A review of the mechanisms and evidence for typical and atypical twinning". American Journal of Obstetrics and Gynecology. 214 (2): 172–91. doi:10.1016/j.ajog.2015.10.930. PMID26548710.