Two anterior decompression and fusion treatments for two-level cervical spondylotic myelopathy: A Meta analysis 
Zhang Wei, Liao Wen-sheng, Wang Li-min, Bao Heng
Chinese Journal of Tissue Engineering Research . 2012, (17): 3134 -3138 .  DOI: 10.3969/j.issn.1673-8225.2012.17.022