1. Allen, D. J., Bilz, M., Leaman, D. J., Miller, R. M., Timoshyna, A. and Window, J. (2014). European Red List of Medicinal Plants. Luxembourg: Publications Office of the European Union. doi 10.2779/907382.
2. Bergamini, A., Bisang, I., Hodgetts, N., Lockhart, N., van Rooy, J. and Hallingbäck, T. (2019). Recommendations for the use of critical terms when applying IUCN red-listing criteria to bryophytes. Lindbergia. doi: 10.25227/linbg.01117
3. Bilz, M., Kell, S.P., Maxted, N. and Lansdown, R.V. (2011). European Red List of Vascular Plants. Luxembourg: Publications Office of the European Union. doi:10.2779/8515
4. Bisang I., Bergamini, A. and Lienhard, L. (2009). Environmental-friendly farming in Switzerland is not hornwort-friendly. Biological Conservation 142: 2104-2113. Doi: 10.1016/j.biocon.2009.04.006
5. Blockeel, T.L., Bosanquet, S.D.S., Hill, M.O. and Preston, C.D. (eds.) (2014). Atlas of British and Irish bryophytes. Newbury, Pisces Publications.