Pei1, Jianyun, et al. “Large-Scale Synthesis of (E)-4-Amino-2-Methylbut-2-En-1-Ol: Key Building Block for the Synthesis of Trans-Zeatin”. Asian Journal of Chemistry, vol. 26, no. 23, Nov. 2014, pp. 8155-7, doi:10.14233/ajchem.2014.17644.