1. Pelargonium sidoides extract for acute respiratory tract infections.
    Timmer A, Gunther J, Rucker G, Motschall E, Antes G, Kern WV. Cochrane Database of Systematic Reviews 2008, Issue 3. Art. No.: CD006323. DOI: 10.1002/14651858.CD006323.pub2.
  2. "Treatment of acute bronchitis in adults with a pelargonium sidoides preparation (EPs 7630): a randomized, double-blind, placebo-controlled trial".
    Chuchalin AG, Berman B, Lehmacher W (Nov 2005). Explore 1 (6): 437-45. doi:10.1016/j.explore.2005.08.009. PMID 16781588
  3. "Efficacy of extract of Pelargonium sidoides in children with acute non-group A beta-hemolytic streptococcus tonsillopharyngitis: a randomized, double-blind, placebo-controlled trial".
    Bereznoy VV, Riley DS, Wassmer G, Heger M (2003). Alternative therapies in health and medicine 9 (5): 68-79. PMID 14526713.
  4. "Efficacy of a pelargonium sidoides preparation in patients with the common cold: a randomized, double blind, placebo-controlled clinical trial".
    Lizogub VG, Riley DS, Heger M (2007). Explore 3 (6): 573-84. doi:10.1016/j.explore.2007.09.004. PMID 18005909.
  5. "Antimicrobial activity of flavonoids from Pelargonium radula (Cav.) L'Herit."
    Acta Pharm. 2005 Dec;55(4):431-435.
  6. Mucolytic agents for chronic bronchitis.
    PJ Poole, PN Black. The Cochrane Library Issue 4, 2000. Oxford, Update Software.
  7. The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systematic review.
    C Stey et al. European Respiratory Journal 2000
  8. Oral acetylcysteine reduces exacerbation rate in chronic bronchitis: a report of a trial organized by the Swedish Society for Pulmonary Diseases.
    Boman G, Backer U, Larsson S, et al. Eur J Respir Dis 1983;64:405-15.
  9. Long-term oral acetylcysteine in chronic bronchitis. A double-blind controlled study.
    Multicenter Study Group. Eur J Respir Dis 1980;61:111:93-108.
  10. Efficacy of oral long-term N-Acetylcysteine in chronic bronchopulmonary disease: A meta-analysis of published double-blind, placebo-controlled clinical trials.
    Grandjean EM, Berthet P, Ruffmann R, Leuenberger P. Clin Ther 2000;22:209-21.
  11. N-Acetylcysteine: Potential for AIDS Therapy
    Mario Roederer, Frank J.T. Staal, Stephen W. Ela, Leonore A. Herzenberg, Leonard A. Herzenberg, Department of Genetics, Stanford University, Stanford, Calif., USA
  12. Are anti-oxidant and anti-inflammatory treatments effective in different subgroups of COPD A hypothesis.
    Van Schayck CP, Dekhuijzen PNR, Gorgels WJMJ, et al. Respir Med 1998;92:1259-64.
  13. Chronic obstructive pulmonary disease and intake of catechins, flavonols, and flavones.
    Tabak C, Arts I, Smit H, Heederik D, Kromhout D, Am J Respir Crit Care Med 2001, 164:61-64
  14. Food and nutrient intakes and asthma risk in young adults.
    Woods R, Walters H, Raven J, Wolfe R, Ireland P, Thien F, Abramson M, Am J Clin Nutr 2003, 78:414-421.
  15. Dietary antioxidants and asthma in adults- population based case-control study.
    Shaheen S, Sterne J, Thompson R, Songhurst C, Margetts B, Buerney P, Am J Respir Crit Care Med 2001, 164:1823-1828
  16. The Honest Herbal
    Tyler, V.E. 1993. 3rd ed. New York: Pharmaceutical Products Press.
  17. Medicinal mushrooms
    Christopher Hobbs, published in Herbs for Health, Jan/Feb 97
  18. Effects of the standardized ginseng extract G115 in patients with chronic bronchitis: a nonblinded, randomised, comparative pilot study.
    Scaglione F, Weiser K, Allessandria M. Clin Drug Invest. 2001;21:41-45.
  19. Efficacy and safety of the standardized Ginseng extract G115 for potentiating vaccination against the influenza syndrome and protection against the common cold.
    Scaglione F, Cattaneo G, Alessandria M, Cogo R. Drugs Exp Clin Res 1996;22:65-72.
  20. A double-blind clinical evaluation of bromelains in the treatment of acute sinusitis.
    Ryan RE. Headache 1967;7(1):13-17.
  21. Study on clinical properties and mechanism of action of Petasites in bronchial asthma and chronic obstructive bronchitis.
    Ziolo G, Samochowiec L. Pharmaceutica Acta Helvetica 1998;72:359-380.
  22. An extract of Petasites hybridus is effective in the prophylaxis of migraine.
    Grossmann WM, Schmidramsl H. Int J Clin Pharmacol Ther 2000;38:430-435.
  23. Impact of Trace Elements and Vitamin Supplementation on Immunity and Infections in Institutionalized Elderly Patients
    A Randomized Controlled Trial, Francois Girodon, MD, PhD; Pilar Galan, MD; Arch Intern Med. 1999;159:748-754.
  24. "Efficacy and safety of an extract of Pelargonium sidoides (EPs 7630) in adults with acute bronchitis. A randomised, double-blind, placebo-controlled trial".
    Matthys H, Eisebitt R, Seith B, Heger M (2003). Phytomedicine 10 Suppl 4: 7-17. PMID 12807337.
  25. The reduction in vitro in viscosity of mucoproteinsolutions by a new mucolytic agent, N-acetylcysteine.
    Sheffner, A. L.Ann. NY Acad. Sci. 106:288 (1963)
  26. The Nutraceutical Revolution.
    Firshein, R. Riverhead Books via Penguin Putnam Inc., New York, USA. 1998:236-237.
  27. Herbal medicines for the treatment of rhinosinusitis: A systematic review.
    Otolaryngology - Head and Neck Surgery , Volume 135 , Issue 4 , Pages 496 - 506 R . Guo , P . Canter , E . Ernst
  28. Effect of ginsenosides, active components of ginseng, on capsaicin-induced pain-related behavior.
    J. J. Naha, J. H. Hahnb, S. Chungc, S. Choia, Y. I. Kimd and S. Y. Nah doi:10.1016/j.physletb.2003.10.071
  29. Ginsenoside Rf, a trace component of ginseng root, produces antinociception in mice
    Jeffrey S. Mogila, *, Young-Hee Shinb, Edwin W. McCleskeyc, Seok-Chang Kimd and Seung-Yeol Nah1, doi:10.1016/S0006-8993(98)00133-4
  30. Treating intermittent allergic rhinitis: a prospective, randomized, placebo and antihistamine-controlled study of Butterbur extract Ze 339
    Dr J. P. Engel (Ingolstadt); Dr J. Horn (Butzbach); Dr W. D. Kaiser (Erfurt); Dr M. Kortum (Schrecksbach); Dr R. Martin (Bad Soden); Dr A. Massing (Offenbach); Dr U. Nemec-Held (Oberursel); Dr S. Sauer (Huttenberg); Dr A. Schapowal (Landquart); Dr R. Schellenberg (Huttenberg); Dr M. Simonsohn (Frankfurt).