4) LEVY L. M. MR phase imaging and cerebrospinal fluid flow in the head and spine.. Neuroradiology. (1990) vol.32, p.399-406.
5) MILHORAT TH. Stenosis of central canal of spinal cord in man: incidence and pathological findings in 232 autopsy cases. J.Neurosurg.. (1994) vol.80, p.716-722.