K. O. Enohumah and C. O. Imarengiae, “Factors Associated with Anesthesia Related Maternal Mortality in a Tertiary Hospital in Nigeria,” Acta Anaesthesiologica Scandinavica, Vol. 50, No. 2, 2006, pp. 206-210. http://dx.doi.org/10.1111/j.1399-6576.2006.00945.x
 G. M. Cooper and J. H. McClure, “Maternal Deaths from Anesthesia. An Extract from Why Mothers Die 200-2002,” the Confidential Enquiries into Maternal Deaths in the United Kingdom: Chapter 9: Anesthesia. British Journal of Anaesthesia, Vol. 94, No. 4, 2005, pp. 417-423. http://dx.doi.org/10. 1093/bja/aei066
 N. J. McDonnel, M. J. Paech, O. M. Clavisi and K. L. Scott, The ANZCA Trials Group, “Difficult and Failed Intubation in Obstetric Anaesthesia: An Observational Study of Airway Management and Complications Associated with General Anesthesia for Caesarean Section,” International Journal of Obstetric Anesthesia, Vol. 17, No. 4, 2009, pp. 292-297. http://dx.doi.org/10.1016/j.ijoa.2008.01.017
 R. V. Johnson, G. R. Lyons, R. C. Wilson and A. P. Robinson, “Training in Obstetric General Anesthesia: A Vanishing Art?” Anesthesia, Vol. 55, No. 2, 2000, pp. 179-183. http://dx.doi.org/10. 1046/j.1365-2044.2000.055002179.x
 K. N. Williams, F. Carli and R. S. Cormack, “Unexpected, Difficult Laryngoscopy: A Prospective Survey in Routine General Surgery,” British Journal of Anaesthesia, Vol. 66, No. 1, 1991, pp. 38-44. http://dx.doi.org/10.1093/bja/66.1.38
 J. M. Davies, S. Weeks, L. A. Crone and E. Pavlin, “Difficult Intubation in the Parturient,” Canadian Journal of Anesthesia, Vol. 36, No. 6, 1989, pp. 668-674. http://dx.doi.org/10.1007/BF03005419
 A. Lee, L. T. Fan, T. Gin, M. K. Karmakar and W. D. Nagen Kee, “A Systematic Review (Meta Analysis) of the Accuracy of the Mallampati Tests to Predict the Difficult Airway,” Anesthesia & Analgesia, Vol. 102, No. 6, 2006, pp. 1867-1878. http://dx.doi.org/10.1213/01.ane.0000217211.12232.55
 T. Shiga, Z. Wajima, T. Inove and A. Sakamoto, “Predicting Difficult Intubation in Apparently Normal Patients: A Meta Analysis of Bedside Screening Test Performance,” Anesthesiology, Vol. 103, No. 2, 2005, pp. 429-437. http://dx.doi.org/10.1097/00000542-200508000-00027
 K. Aoyama, E. Yasunaga, I. Takenaka, T. Kadoya, T. Sata and A. Shigematsu, “Positive Pressure Ventilation during Fiberoptic Intubation: Comparison of the Laryngeal Mask Airway, Intubating Laryngeal Mask and Endoscopic Mask Techniques,” British Journal of Anaesthesia, Vol. 88, No. 2, 2002, pp. 246-254. http://dx.doi.org/10.1093/bja/88.2.246
 F. Zand and A. Amini, “Use of Laryngeal Tube-S? for Airway Management and Prevention of Aspiration after a Failed Tracheal Intubation in a Parturient,” Anesthesiology, Vol. 102, No. 2, 2005, pp. 481-483. http://dx.doi.org/10.1097/00000542-200502000-00039
 R. Awan, J. P. Nolan and T. M. Cook, “Use of a Pro-Seal? Laryngeal Mark Airway for Airway Maintenance during Emergency Caesarean Section after Failed Tracheal Intubation,” British Journal of Anaesthesia, Vol. 92, No. 1, 2004,pp. 144-146. http://dx.doi.org/10.1093/bja/aeh019
 E. A. Djabatey and P. M. Barclay, “Difficult and Failed Intubation in 3430 Obstetric General Anesthetics,” Anaesthesia, Vol. 64, No. 11, 2009, pp. 1168-1171. http://dx.doi.org/10.1111/j.1365-2044.2009.06060.x
 G. E. Lewis, “The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving Mother’s Lives; Reviewing Maternal Deaths to Make Motherhood Safer-2003-2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom,” CEMACH, London, 2007.
 C. Keller, J. Brimacombe, M. Boehler, A. Loeckinger and F. Puehringer, “The Influence of Cuff Volume and Anatomical Location on Pharyngeal, Esophageal and Tracheal Mucosal Pressures with the Esophageal Tracheal Combitube,” Anesthesiology, Vol. 96, 2002, pp. 1074-1077.