1. Additional heart rate—an indicator of psychological activation;Blix;Aerospace Medicine,1974
2. Heart rate and oxygen consumption during active psychological challenge: The effects on level of difficulty;Caroll;Psychophysiology,1986
3. Spectral analysis of heart rate variability as an indicator of driver fatigue;Egelund;Ergonomics,1982
4. Performance and subjective measures of workload in multi-task environments;Eggemeier,1991
5. Respiratory sinus arrhythmia: Physiological basis, quantitative methods, and clinical implications;Grossman,1986