Binocular Vertical DiplopiaMayo Clin Proc 73:55-66, Brazis,P.W.&Lee,A.G., 1998
Acquired Lesions of the Fourth Cranial NerveBrain 93:567, Berger,J.,et al, 1970
Eye MovementsJNNP 59:115-125, Shaunak,S.,et al, 1995