1. Rimpler, H.Biogene Arzneistoffe; Dt-Apotheken Verlag: Stuttgart, Germany, 1995; pp 363−365.
2. Burdock, G. A.Fenaroli's Handbook of Flavour Ingredients, 3rd ed.; CRC Press: Boca Raton, FL, 1995; pp 241−242, 833−843, 860−861.
3. Burrows, G. Rhubarb. InFruit Processing; Arthey, D., Ashurst, P. R., Eds.; Aspen Publisher: Gaithersburg, MD, 2001; p 169.