1. Boyce, K.C., Cody, G. D., Fogel, M.L., et al., Chemical evidence for cell wall lignification and the evolution of tracheids in early Devonian plants, Int. J. Plant Sci., 2003, vol. 164, no. 5, pp. 691–702.
2. Broushkin, A.V. and Gordenko, N.V., The oldest vascular plants and their impact on the environment, in Rannyaya kolonizatsiya sushi (Early Colonization of Land), Moscow: Paleontol. Inst. Ross. Akad Nauk, 2012, pp. 157–176.
3. Broushkin, A.V. and Gordenko, N.V., Devonian flora of the Middle–Lower Volga region, Fitoraznoobr. Vostochnoy Evropy, 2016, vol. 10, no. 1, pp. 14–33.
4. Chirkova-Zalesskaya, E.F., Deleniye terrigennogo devona Uralo-Povolzh’ya na osnovanii iskopayemykh rasteniy (Division of the Terrigenous Devonian of the Ural-Volga Region on the Basis of Fossil Plants), Moscow: Publ. House USSR Acad. Sci., 1957.
5. Davin, L.B. and Lewis, N.G., Lignin primary structures and dirigent sites, Curr. Opin. Biotechnol. 2005, no. 16, pp. 407–415.