Katherine Threlkeld

I know Katherine (or Kathryn) Threlkeld is the name of my dad's grandmother. I'm not sure which side she fell on. My dad's name was Richard Lee Cory-born 11/10/1934, died 3/20/1995. My grandparents names were Mary Myrtle (Cory)-not sure of maiden name(could've been threlkeld) and Elmer Eugene Cory, born January 19-don't know year. My dad married Judith Ann Stormer (12/19/1940-10/28/1990) on March 16, 1957.