%0 Journal Article %A PDA %T PDA Comments: USP on Microbiological Evaluation of Clean Rooms and Other Controlled Environments <1116> %D 1997 %J PDA Journal of Pharmaceutical Science and Technology %P 222-226 %V 51 %N 6 %U https://journal.pda.org/content/pdajpst/51/6/222.full.pdf