Most likely you will find them in the archives of the Federal District Court that served that community (in this case, Lorian, Ohio) at the time of his naturalization.
You should be able to get both the Petition (application) dated at least five years in advance of the actual naturalization and the Naturalization document itself. The Petition often contains more useful information than does the final document.
If the Court there no longer has them, they can direct you to where they are stored.
Good luck and good hunting.