The following reference work is cited in this example problem:
Shahim, K., Drezet, J.-M., Molinari, J.-F., Sinkus, R., & Momjian, S.
(2010). Finite element analysis of normal pressure hydrocephalus: Influence of
CSF content and anisotropy in permeability. Applied Bionics and
Biomechanics. 7(3), 187-197.
