Irianto, K. A., and M. K. Tumbelaka. “A Case Series of Eight Scoliosis Patients Undergone Pedicle Screw Placement With Freehand Technique: Study for Safety and Accuracy”. Medical Journal of Indonesia, Vol. 29, no. 2, July 2020, pp. 222-7, doi:10.13181/mji.cr.191978.