Alamdaran, A., Pourhoseini, M. T., Jafari, S. A., Shojaeian, R., Feyzi, A., & Pezeshki Rad, M. "Ultrasonographic Evaluation of the Sacrococcyx and Spinal Canal in Children with Constipation", Journal of Pediatric Perspectives, 5, 12, 2017, 6267-6274. doi: 10.22038/ijp.2017.23759.2010