Comparison of programmable shunt valves vs standard valves for communicating hydrocephalus of adults: a retrospective analysis of 407 patients.
http://www.ncbi.nlm.nih.gov/pubmed/15639519
A randomized, controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus.
http://www.ncbi.nlm.nih.gov/pubmed/10598708