Bethel Book maps
Christians on the Oregon Trail by Jerry Rushford
Making Disciples in Oregon by C.F. Swander
Polk County Historical Deeds
https://apps2.co.polk.or.us/DigitalResearchRoom
Churches of Christ & Christian Churches
in the Pacific Northwest
http://ncbible.org/nwh/orcola.html
Bethel Cemetery
BLM records
Surveyed portions of Oregon
Aerial photos
https://oregondigital.org/collections/aerial-photos-mid-willamette
Oregon State archives
https://guides.library.oregonstate.edu/subject-guide/551-Maps
Townships