1. Wide bandwidth fetal phonography using a sensor matched to the compliance of the mother's abdominal wall;Talbert;IEEE Trans Biomed Eng,1986
2. The spectrum of the fetal PCG as an indicator of fetal maturity;Nagel,1986
3. Progress in fetal monitoring by improved data acquisition and interpretation;Nagel;IEEE EMB Mag,1984
4. Anwendbarkeit frequenzanalytischer Methoden in der Phonokardiographie;Bödecker,1982
5. The Wigner distribution function and its optical production;Bartelt;Optics Commun,1980