Jeffrey H. Silber, Sean K. Kennedy, Orit Even-Shoshan, Wei Chen, Rachel E. Mosher, Ann M. Showan, David E. Longnecker,
Anesthesiologist board certification and patient outcomes. Anesthesiology. ,vol. 96, pp. 1044- 1052 ,(2002) ,
10.1097/00000542-200205000-00004