Name	Info	Provider	Link
	subscription/membership/fee required	Atypon	https://journals.sagepub.com/doi/10.1177/104063871002200128?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub 0pubmed
SILVA SSU Database	free resource	SILVA	http://www.arb-silva.de/search/show/ssu/pubid/20093702