Hirth, C., Obrig, H., Valdueza, J., Dirnagl, U., & Villringer, A. (1997). Simultaneous assessment of cerebral oxygenation and hemodynamics during a motor task. A combined near infrared and transcranial doppler sonography study. Advances in Experimental Medicine and Biology, 411, 461-469. doi:PMID: 9269463 [PubMed - indexed for MEDLINE].