Primary references

• Macbride, J.F. 1934. New or renamed spermatophytes mostly Peruvian. Candollea 5: 346–402. Reference page. 

Additional references

• Giraldo-Cañas, D. 2011. Las Marcgraviaceae de Colombia: Inventario, diversidad, endemismo y distribución. Bioetnia 8: 28–39. PDF Reference page. 

• Macbride, J.F. 1956. Marcgraviaceae. In Flora of Peru. Publications of the Field Museum of Natural History, Botanical Series 13(3A/2): 703–717. BHL Reference page. 

Links

• International Plant Names Index. 2019. Marcgravia williamsii. Published online. Accessed 03 February 2019.

• GBIF

• Hassler, M. 2019. Marcgravia williamsii. World Plants: Synonymic Checklists of the Vascular Plants of the World (2019). In: Roskov Y., Abucay L., Orrell T., Nicolson D., Bailly N., Kirk P., Bourgoin T., DeWalt R.E., Decock W., De Wever A., Nieukerken E. van, Zarucchi, J., Penev L., eds. 2019. Species 2000 & ITIS Catalogue of Life. Published on the internet. Accessed: 2019 February 03.

• Tropicos.org 2019. Marcgravia williamsii. Missouri Botanical Garden. Published on the internet. Accessed: 03 February 2019.

• Marcgravia williamsii in Bernal, R., Gradstein, S.R. & Celis, M. (eds.). 2015. Catálogo de plantas y líquenes de Colombia. Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá. Accessed: 04 May 2019.

• Tropicos.org: Peru Checklist: Marcgravia williamsii. Missouri Botanical Garden. Published on internet. Accessed: 03 February 2019.