1.An improved method for quantification of very long chain fatty acids in plasma Clinical Biochemistry, Volume 27, Issue 3, June 1994, Pages 183-186 Hilary Vallance, Derek Applegarth 2. Stellaard F, ten Brink HJ, Kok RM, van den Heuvel L,Jakobs C. Stable isotope dilution analysis of very long chain fatty acids in plasma, urine, and amniotic fluid by electron capture negative ion mass fragmentography. Clin Chim Acta 192:133–144, 1990.