Payne J. Bleeding disorders. Patient. https://patient.info/doctor/bleeding-disorders. Updated February 28, 2017. Accessed December 2020.
Prothrombin time and international normalized ratio (PT/INR). Lab Tests Online. https://labtestsonline.org/tests/prothrombin-time-and-international-normalized-ratio-ptinr. Updated September 22, 2020. Accessed December 2020.
Yang R, Moosavi L. Prothrombin time. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK544269/. Updated July 10, 2020. Accessed December 2020.