Improving perioperative pain management: a preintervention and postintervention study in 7 developing countries oleh Ruth Zaslansky, C. Richard Chapman, Philipp Baumbach, Adem Bytyqi, José M. Castro Lopes, Sean Chetty, Andreas Kopf, Li Li, Lim Ern Ming, Olayinka Olawoye, Jane Rizza Parico, Olaitan Soyannwo, Dusica Stamenkovic, Hongwei Wang, Winfried Meissner