German, D. A. “Notes on Taxonomy of Erysimum (Erysimeae, Cruciferae) of Russia and Adjacent States. II. Middle Asian Purple- and Orange-Flowered Species”. Turczaninowia, Vol. 24, no. 3, Oct. 2021, pp. 111-28, doi:10.14258/turczaninowia.24.3.9.