1. Amniocentesis;Schwarz;Clinical Obstetrics and Gynaecology,1975
2. Iatrogenic Foetal Distress;Schifrin;International Anaesthesiology Clinics,1973
3. Schwarz , R. H. op. cit
4. Ibid.
5. Foetal Blood Sampling by Foetoscopy in Pregnant Ewes;Aarnoudse;European Journal of Obstetrics, Gynaecology and Reproductive Biology,1978