Grimm W, Muller HH. A randomized controlled trial of the effect of fluid extract of Echinacea purpurea on the incidence and severity of colds and respiratory infections. Am J Med. 1999; 106: 138-143.
 Patel T, Crouch A, Dowless K, Freier D. Acute effects of oral administration of a glycerol extract of Echinacea purpurea on peritoneal exudate cells in female Swiss mice. Brain Behav Immun. 2008; 22: 39.
 Cepae BA. WHO monographs on selected medicinal plants. Geneva: World Health Organization, 1999.
 Barnes J, Anderson LA, Gibbons S, Phillipson JD. Echinacea species (Echinacea angustifolia (DC.) Hell., Echinacea pallida (Nutt.) Nutt, Echinacea purpurea (L.) Moench): a review of their chemistry, pharmacology and clinical properties. J Pharm Pharmacol. 2005; 57: 929-954.
 Coopstead C. Pathophysiology. Missouri: Saunders, 2010.
 Mast EE, Margolis HS, Fiore AE, Brink EW, Goldstein ST, Wang SA, Moyer LA, Bell BP, Alter MJ. Comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practice (ACIP) part 1: immunization of infants, children, and adolescents. MMWR Recomm Rep. 2005; 54: 1-31.
 Hollinger FB, Lau DT. Hepatitis B: the pathway to recovery through treatment. Gastroenterol Clin N. 2006; 35: 895-931.
 Lai CL, Yuen MF. The natural history and treatment of chronic hepatitis B: a critical evaluation of standard treatment criteria and end points. Ann Intern Med. 2007; 147: 58-61.
 Gopal DV, Rosen HR. Abnormal findings on liver function tests. Interpreting results to narrow the diagnosis and establish a prognosis. Postgrad Med. 2000; 107: 100-102.
 Kasper DL, Fauci AS, Longo DL, Braunwald E, Hauser SL, Jameson JL. Harrison's principles of internal medicine. 16th ed. New York: McGraw-Hill, 2005.
 Miller LG. Selected clinical considerations focusing on known or potential drug-herb interaction. Arch Intern Med. 1998; 158: 2200-2211.
 EBSCO CAM Review, Proposed natural treatments for viral hepatitis; Available from: http://www.med.nyu.edu/content. 2014.
 Rusu MA, Tamas M, Puica C, Roman I, Sabadas M. The hepatoprotective action of ten herbal extracts in CCl4 intoxicated liver. Phytother Res. 2005; 1: 744-749.