Valdueza, J. M., Balzer, J. O., Villringer, A., Vogl, T. J., Kutter, R., & Einhaeupl, K. M. (1997). Changes in blood flow velocity and diameter of the middle cerebral artery during hyperventilation: Assessment with MR and transcranial Doppler sonography. American Journal of Neuroradiology, 18(10), 1929-1934.