Hi Bernd -
Findagrave.com has this listing that appears possibly to be him. The man’s wife Mary and a son Anthony Joseph Robke are also buried in the same cemetery.
The person who posted this, Pam Gunkel, has posted a total of 20 listings over the past 2 1/2 years. All but one of those people have been in the same cemetery in Kenton Vale, Kenton County, Kentucky.
I’m thinking she might be a relative of theirs - and you could contact her via the email shown on that site.