Hart, R. A., Prendergast, M. A., Roberts, W. G., Nesbit, G. M., & Barnwell, S. L. (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)