An isotope dilution-liquid chromatography-tandem mass spectrometry based candidate reference measurement procedure for the simultaneous quantification of 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in human serum and plasma. - Kandler K; Singh N; Bauland F; Fux E; Geistanger A; Geletneky C; Taibon J (Clinical chemistry and laboratory medicine, 2025)