"So-Called Dollars" refer to a category of commemorative and novelty coins that were issued primarily in the United States. They often feature designs that commemorate specific events or individuals but are not legal tender. The Hibler and Kappen reference is to the authors of "So-Called Dollars," a standard catalog detailing these tokens. The 1885 issue is particularly noted for its depiction of events related to the centennial celebrations and has become popular among collectors for its historical significance and unique designs.