Holmen, Linda; Santella-Johnson, Mary; Watterson, Bill (1993). Teaching with Calvin and Hobbes. Cover and supplementary art by Jan Roebken. Fargo, North Dakota: Playground Publishing. ISBN1-878849-15-8.
Holmen, Linda; Santella-Johnson, Mary; Watterson, Bill (1993). Teaching with Calvin and Hobbes. Cover and supplementary art by Jan Roebken. Fargo, North Dakota: Playground Publishing. ISBN1-878849-15-8.