Butterflies of Darke County - Presents photos and species accounts of butterflies found within the county. www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/chklist/states/counties/oh_37.htm
Darke County Ground-Water Resources - Factsheet providing information on ground-water resources in the county. ohioline.osu.edu/aex-fact/0490_19.html
Water Resources of Darke County - Factsheet providing information on water resources and drinking-water quality in the county. ohioline.osu.edu/aex-fact/0480_19.html
