Cemeteries are often documented by just the stones that are there. It's always possible that a stone was there, but broken or knocked down through the years. Sometimes the only documentation of where someone was buried is in the old obituaries. It became law that all births and deaths were to be reported in the year of 1882. If anyone you are looking for died in 1882 or later, their death record should tell where they were buried. But then, it was the doctors who were to report these births and deaths and old newspapers tell that some doctors neglected to abide by the law when it first came out.