Saier, M.H., Jr. (1998). „Molecular phylogeny as a basis for the classification of transport proteins from bacteria, archaea and eukarya”. Adv. Microb. Physiol.40: 81-136. PMID9889977.
Novak, R., Braun, J.S., Charpentier, E. and Tuomanen, E. (1998). „Penicillin tolerance genes of Streptococcus pneumoniae: the ABC-type manganese permease complex Psa”. Mol. Microbiol.29: 1285-1296. PMID9767595.