American Psychological Association (APA)
parts per million. (n.d.). Glossary of Biotechnology for Food and Agriculture. Retrieved June 8, 2023, from website: http://www.expertglossary.com/definition/parts-per-million.
Chicago Manual of Style (CMS)
parts per million. www.fao.org. Glossary of Biotechnology for Food and Agriculture. UN Food and Agriculture Organization. http://www.expertglossary.com/definition/parts-per-million (accessed: June 8, 2023).
Modern Language Association (MLA)
"parts per million." Glossary of Biotechnology for Food and Agriculture. UN Food and Agriculture Organization. 8 June. 2023 http://www.expertglossary.com/definition/parts-per-million.