Li, G., Passias, P., Kozanek, M., Shannon, B. D., Li, G., Villamil, F., . . . Wood, K. B. (2009). Interobserver reliability and intraobserver reproducibility of powers ratio for assessment of atlanto-occipital junction: Comparison of plain radiography and computed tomography. Springer-Verlag.

Li, Gang, Peter Passias, Michal Kozanek, Brian D. Shannon, Guoan Li, Fernando Villamil, Christopher M. Bono, Mitchel Harris, a Kirkham B. Wood. Interobserver Reliability and Intraobserver Reproducibility of Powers Ratio for Assessment of Atlanto-occipital Junction: Comparison of Plain Radiography and Computed Tomography. Springer-Verlag, 2009.

Li, Gang, et al. Interobserver Reliability and Intraobserver Reproducibility of Powers Ratio for Assessment of Atlanto-occipital Junction: Comparison of Plain Radiography and Computed Tomography. Springer-Verlag, 2009.