Bumann, D., Metzger, W. G., Mansouri, E., Palme, O., Wendland, M., Hurwitz, R., et al. (2001). Safety and immunogenicity of live recombinant Salmonella enterica serovar Typhi Ty21a expressing urease A and B from Helicobacter pylori in human volunteers. Vaccine, 20(5-6), 845-852.