2RINGELSTEIN B, KAHLSCHEUER B,NIGGEMEYER E, et al. Transcranial doppler sonography: anatomical landmarks and normal velocity value[J]. Ultrasound in Medicine & Biology,1990 16(8):745-761.
3SORTEBERG W, LANGMOEN L A, LINDEGAARD K F.Side-to-side differences and day-to-day variations of transcranial doppler parameters in normal subjects[J]. J Ultrasound Med,1990,9(7) :410-416.