1. Parer J T (1997) Handbook of fetal heart rate monitoring. 2nd ed. Philadelphia, PA: Saunders
2. Rooth G, Huch A, Huch R (1987) Guidelines for the use of fetal monitoring. Int J Gynaecol Obstet 25: 159–67
3. Geijn H P V (1996) Developments in CTG analysis. Bailliere’s Clin Obstet Gynaecol 10:2: 185–209
4. Dawes G, Moulden M, Sheil O, Redman C W G (1992) Aproximate entropy, a statistic of regularity, applied to fetal heart rate data before and during labour. Obstet Gynecol 80:5:763–8
5. Arduini D, Rizzo G, Piana G, Bonalumi A, Brambilla P, Romanini C (1993) Computerized Analysis of Fetal Heart Rate: I. Description of the System (2CTG). J Matern Fetal Invest 3: 159–163