Bohl DD, Haws BE, Khechen B, Patel DV, Mayo BC, Ahn J, Louie PK, Cardinal KL, Guntin JA, Singh K. Impact of the Number of Levels on Adverse Events and Length of Stay Following Posterior Lumbar Fusion Procedures. Clin Spine Surg. 2019 04; 32(3):120-124.