Radiographic and anatomic basis of endoscopic anterior craniocervical decompression: a comparison of endonasal, transoral, and transcervical approaches - Baird,C.J.; Conway,J.E.; Sciubba,D.M.; Prevedello,D.M.; Quiñones-Hinojosa,A.; Kassam,A.B. (Neurosurgery, 2009)