Stickel et al., 2000. Public Health Nutr., 3 (4A): 501-508 Document reference Stickel, F. ; Seitz, H. K., 2000. The efficacy and safety of comfrey. Public Health Nutr., 3 (4A): 501-508Web https://doi.org/10.1017/S1368980000000586Citation key Stickel et al., 2000Datasheets Russian comfrey (Symphytum × uplandicum)
