European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
Kose KC, Isik C, Altinel L, Ates A, Ozdemir M. Easy retrieval of polyaxial tulip-head pedicle screws by “U” rod technique. European Spine Journal. 2009 Jul 18;19(1):144–6. doi: 10.1007/s00586-009-1096-4.