A new robust 2-D spectral estimation method and its application in cardiac data analysis. - Chrysostomos L. Nikias; Peter D. Scott; John H. Siegel (ICASSP, 1982)

A Geometric Model for Physiologic State Classification and Severity Classification of Critically Ill Patients. - Herman P. Friedman; John H. Siegel (Electron. Notes Discret. Math., 1999)