Hart, R. ., Prendergast, M. ., Roberts, W. ., Nesbit, G. ., & Barnwell, S. . (1969). Proximal junctional acute collapse cranial to multi-level lumbar fusion: a cost analysis of prophylactic vertebral augmentation. The Spine Journal : Official Journal of the North American Spine Society, 8(6), 875-81. https://doi.org/10.1016/j.spinee.2008.01.015 (Original work published 1969)