Deep vein thrombosis. Updated May 5, 2014. Accessed May 7, 2014.
Matic PA, Vlajinac HD, et al. Chronic venous disease: Correlation between ultrasound findings and the clinical, etiologic, anatomic and pathophysiologic classification. Phlebology. 2013 Jul 15 [Epub ahead of print].
Ultrasound—venous (extremities). Radiological Society of North America Radiology Info website. Available at:
http://www.radiologyinfo.org/en/info.cfm?PG=venousus. Updated August 27, 2013. Accessed May 7, 2014.
Venous ultrasound of the legs (lower extremity doppler). Harvard Health Publications. Available at: http://www.health.harvard.edu/diagnostic-tests/venous-ultrasound-of-the-legs.htm. Accessed May 7, 2014.
FamilyDoctor.org - American Academy of Family Physicians
RadiologyInfo.org - Radiological Society of North America
Canadian Family Physicians