N. . Opartkiattikul, P. . Tientadakul, and W. . Wongtiraporn, “Evaluation of the Activated Partial Thromboplastin Time (aPTT) Sensitivity to Unfractionated Heparin Using Three Commercial Reagents: Implication for Therapeutic Range”, Siriraj Med J, vol. 57, no. 12, pp. 537–540, Dec. 2005.