Stable isotope dilution analysis of N-acetylaspartic acid in CSF, blood, urine and amniotic fluid: accurate postnatal diagnosis and the potential for prenatal diagnosis of Canavan disease. - Jakobs,C.; ten Brink,H.J.; Langelaar,S.A.; Zee,T.; Stellaard,F.; Macek,M. (J Inherit Metab Dis, 1991)