Degenerative Diseases of the Nervous System, Progressive Supranuclear Palsy
Adams & Victors Principles of Neurology, Chp 39, pg 1096, Ropper, A.H.,et al, 2014
Ocular Motor Manifestations of Brainstem & Cerebellar Dysfunction
Chap 9, p 104 Neuro-Ophthalmol ed J. L. Smith., Daroff,R.B., 1850