UFO Survey Paper:

“Survey of Unidentified Aerial Phenomenon 
Reports in Delaware County, Ohio”

by I. Scott, Department of Physiology, 
The Ohio State University, Columbus, Ohio

(The Ohio Journal of Science 
(Volume 87, No. 1, March 1987), 
The Ohio Academy of Science, Columbus, Ohio)

Thirty-one percent of the 62 respondents reported UFO observations, according to I. Scott:

https://kb.osu.edu/dspace/handle/1811/23178

Wikipedia article: “Delaware County, Ohio”:

https://en.wikipedia.org/wiki/Delaware_County,_Ohio

Map of Ohio highlighting Delaware County (text by Wikipedia)

(wikimedia.org image)