Witters E, Vanhoutte K, Dewitte W, et al. Analysis of cyclic nucleotides and cytokinins in minute plant samples using phase system switching capillary electrospray liquid chromatography tandem mass spectrometry. Phytochemical Analysis. 1999;10(3):143-151. doi:10.1002/(SICI)1099-1565(199905/06)10:3&#38;lt;143::AID-PCA441&#38;gt;3.0.CO;2-G