1920 Spirometry. Unknown type and brand of spirometer. From: University of Iowa Digital Library. http://digital.lib.uiowa.edu/cdm/singleitem/collection/ictcs/id/7549/rec/9
1920 Spirometry. Unknown type and brand of spirometer. From: University of Iowa Digital Library. http://digital.lib.uiowa.edu/cdm/singleitem/collection/ictcs/id/7549/rec/9