References:
- Doppler ultrasound: What is it used for? - (http://www.mayoclinic.org/doppler-ultrasound/expert-answers/faq-20058452)
- Doppler ultrasonography - (http://en.wikipedia.org/wiki/Duplex_ultrasonography)
- Doppler echocardiography - (http://en.wikipedia.org/wiki/Doppler_echocardiography)
- Transcranial Doppler - (http://en.wikipedia.org/wiki/Transcranial_Doppler)
Editor: Sudha Bhat
Technically Checked by: Lingaraj