In 1975 Richard E. James III found a ninth type, after reading about Kershner's results in Martin Gardner's "Mathematical Games" column in Scientific American magazine of July 1975 (reprinted in Gardner (1988)).
I 1975 fandt Richard E. James III yderligere en niende type, efter han havde læst om Kershners resultater i Martin Gardners kolonne "Mathematical Games" i Scientific American i juli 1975.