{{Terrazas, T., Arias, S. & Arreola, H. 2017. Mammillaria backebergiana (amended version of 2013 assessment). The IUCN Red List of Threatened Species 2017: e.T152703A121545709. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T152703A121545709.en. Downloaded on 10 June 2020.}}