8Siriphanich J, Kader AA. Effects of CO2 on total phenolics phenylalanine ammonia lyase and polyphenol oxidase in lettuce tissue. J Amer Soc Hort Sci, 1985, 110 (2): 249-253
9Bendau DS, Gregory RPE. Purifcation of phenol oxidases In Pridham JB ( ed ) . Enzyme Chemistry of Phenolic Compounds. Oxford: Pergamon Press, 1963, 7-24
10Mayer AM, Harel E, Ben - Shaul R. Assay of catechol oxidase a critical comparison of methods. Phytochem, 1966, 5:783 -789