1. Mythology and customs associated with twins;Corney,1975
2. A recent twin murder in South Africa;Harris;Folklore,1922
3. Abandonment and exposure;Giles,1908
4. Benefits of ultrasonic screening of a pregnant population;Grennert;Acta Obstet Gynecol Scand Suppl,1978
5. Scottish Perinatal and Infant Mortality and Morbidity Report 2002