Hammond RW, Owens RA (2006). "Viroids: New and Continuing Risks for Horticultural and Agricultural Crops". APSnet Feature Articles. doi:10.1094/APSnetFeature-2006-1106.
Di Serio F, Owens RA, Li SF, Matoušek J, Pallás V, Randles JW, Sano T, Verhoeven JT, Vidalakis G, Flores R (November 2020). Zerbini FM, Sabanadzovic S (eds.). "Viroids". Archived from the original on December 2, 2020. Retrieved February 3, 2021.
Di Serio F, Owens RA, Li SF, Matoušek J, Pallás V, Randles JW, Sano T, Verhoeven JT, Vidalakis G, Flores R (November 2020). Zerbini FM, Sabanadzovic S (eds.). "Viroids". Archived from the original on December 2, 2020. Retrieved February 3, 2021.