I've found that tacking 'pdf' onto search queries gets through some of the SEO garbage. For instance I did 'home dust filtration pdf' and found this pdf: https

I've found that tacking 'pdf' onto search queries gets through some of the SEO garbage. For instance I did 'home dust filtration pdf' and found this pdf: https://www.epa.gov/sites/default/files/2018-07/documents/residential_air_cleaners_-_a_technical_summary_3rd_edition.pdf https://www.epa.gov/sites/default/files/2018-07/documents/re... which cites this paper about deposition rates of different particle sizes: https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860943 https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=86094...