Gurley BJ, Wang P, Gardner SF: Ephedrine-type alkaloid content of nutritional supplements containing Ephedra sinica (Ma-huang) as determined by high performance liquid chromatography. J Pharm Sci. 1998 Dec;87(12):1547-53. PMID10189265
Abourashed EA, El-Alfy AT, Khan IA, Walker L: Ephedra in perspective--a current review. Phytother Res. 2003 Aug;17(7):703-12. PMID12916063
Haller CA, Benowitz NL: Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med. 2000 Dec 21;343(25):1833-8. PMID11117974
Bent S, Tiedt TN, Odden MC, Shlipak MG: The relative safety of ephedra compared with other herbal products. Ann Intern Med. 2003 Mar 18;138(6):468-71. PMID12639079