R. M. A. Al Hayali, M. K. Hammo, T. M. Al-Saegh, and D. J. S. Al-Habbo, “Pulmonary embolism, seasonal variations in admission to hospital, and the association of calf deep vein thrombosiswith pulmonary embolism”, Ann. coll. Med. Mosul , vol. 35, no. 2, pp. 140–146, Dec. 2009.