https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052208.pdf
http://pubs.cahnrs.wsu.edu/publications/wp-content/uploads/sites/2/publications/FS170E.pdf
https://www.nature.org/content/dam/tnc/nature/en/documents/rethink-soil-executive-summary.pdf
http://www.css.cornell.edu/extension/soil-health/1concepts.pdf
https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/class/data/?cid=nrcs142p2_053588
https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_053293.pdf
https://scdhec.gov/sites/default/files/Library/OR-1705.pdf
https://archive.epa.gov/wastes/conserve/tools/greenscapes/web/pdf/compost-guide.pdf
https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1066.pdf
https://www.pca.state.mn.us/sites/default/files/w-hhw1-21.pdf
https://www.lakemt.gov/solidwaste/PDF/Composting1.pdf
http://compostcrew.com/The%20List.pdf
https://new.cloudvault.usda.gov/index.php/s/XiiqkG2DqKHbH6b/download