Ultrasound-guided facet joint injections in the middle to lower cervical spine: a CT-controlled sonoanatomic study. - Galiano,K.; Obwegeser,AA.; Bodner,G.; Freund,MC.; Gruber,H.; Maurer,H.; Schatzer,R.; Fiegele,T.; Ploner,F. (Clin J Pain, 2006)